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Co_superalloys_comp3(1).txt
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Co_superalloys_comp3(1).txt
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FN Clarivate Analytics Web of Science
VR 1.0
PT J
AU Smialek, JL
Gray, S
AF Smialek, James L.
Gray, Simon
TI Type II Hot Corrosion Screening Tests of a Cr2AlC MAX Phase Compound
SO OXIDATION OF METALS
AB Low-temperature hot corrosion tests were performed on bulk Cr2AlC MAX phase compounds for the first time. This material is a known alumina-former with good oxidation and Type I high-temperature hot corrosion resistance. Unlike traditional (Ni,Co)CrAl alumina formers, it contains no Ni or Co that may react with Na2SO4 salt deposits needed to form corrosive mixed (Ni,Co)SO4-Na2SO4 eutectic salts active in Type II hot corrosion. Cr2AlC samples coated with 20K(2)SO(4)-80Na(2)SO(4) salt were exposed to 300ppm SO2 at 700 degrees C for times up to 500h. Weight change, recession, and cross-sectional microstructures identified some reactivity, but much reduced (<1/10) compared to a Ni(Co) superalloy baseline material. Layered Al2O3/Cr2O3 scales were indicated, either separated by or intermixed with some retained salt. However, there was no conclusive indication of salt melting. Accelerated oxidation was proposed to explain the results, and coarse Cr7C3 impurities appeared to play a negative role. In contrast, the superalloy exhibited outer Ni(Co) oxide and inner Cr2O3 scales, with Cr-S layers at the interfaces. Massive spallation of the corrosion layers occurred repeatedly for the superalloy, but not at all for Cr2AlC. This indicates some potential for Cr2AlC as LTHC-resistant coatings for superalloys.
RI Smialek, James L./AAD-7588-2019
OI Smialek, James L./0000-0003-4310-5569; Gray, Simon/0000-0003-1265-0759
SN 0030-770X
EI 1573-4889
PD DEC
PY 2018
VL 90
IS 5-6
BP 555
EP 570
DI 10.1007/s11085-018-9857-2
UT WOS:000449331500002
ER
PT J
AU Ojo, OA
Aina, O
AF Ojo, O. A.
Aina, O.
TI On the Effect of Liquid-State Diffusion on Isothermal Solidification
Completion Time During Transient Liquid-Phase Bonding of Dissimilar
Materials
SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND
MATERIALS SCIENCE
AB A study of transient liquid-phase bonding (TLPB) of dissimilar materials consisting of a nickel-based superalloy and a cobalt material is performed. In contrast to the assumption that rapid atomic diffusion in the liquid would reduce the processing time, t (f), required to completely eliminate the liquid phase from the joint region through diffusional solidification, the occurrence of liquid-state diffusion significantly prolonged the processing time t (f). This finding is crucially important to the TLPB of dissimilar materials.
SN 1073-5623
EI 1543-1940
PD MAY
PY 2018
VL 49A
IS 5
BP 1481
EP 1485
DI 10.1007/s11661-018-4572-9
UT WOS:000428844800011
ER
PT B
AU Guro, VP
AF Guro, Vitaliy P.
GP TANGER LTD
TI AMMONIUM PERRHENATE PURIFICATION AND RHENIUM RECOVERY FROM
HEAT-RESISTANT RHENIUM-NICKEL SUPERALLOYS
SO 21ST INTERNATIONAL CONFERENCE ON METALLURGY AND MATERIALS (METAL 2012)
CT 21st International Conference on Metallurgy and Materials
CY MAY 23-25, 2012
CL Brno, CZECH REPUBLIC
SP TANGER, VSB - TU OSTRAVA, ASM Int, Czech Soc New Mat & Technologies (CSNMT)
AB An enterprise for purification of crude ammonium perrhenate purchased at Central Asia region as well as for rhenium recovery from Re-Ni heat resistant superalloys wastes of CMSX-4 & CMSX-10 types, has started its activity at Czech Republic. First type of rhenium raw material - the initial ammonium perrhenate (APR), for example, according to Uzbekistan's Standard TU 48-7-1-90, type AR-0, contains: Re not less than 69 % mass.; impurities, ppm: P 90, S 200, Fe 50, Si 20, Mn 2; Mg 8, Ni 2, Al 5, Mo 5, Ca 10, Cu 3, K 40-70; Na 40. By means of ion exchange on Purolite resins surface and electrodialysis approach the content of above mentioned impurities in NH4ReO4 salt might be significantly reduced (K < 20). Second type of rhenium raw material - metallic wastes of superalloys of CMSX-4 & CMSX-10 type contains, % mass: Re 3-6; Cr 6.5; Co 9; Mo 0.6; W 6; Ta 6.5; Re 3; Al 5.6; Ti 1; Hf 0.1; Ni 61.7. The resulting APR is of high quality too. Powdery metal rhenium might be produced from this APR by means of its high-temperature reduction by gaseous hydrogen. The purity of obtained metallic rhenium is generally determined by purity of APR applied.
BN 978-80-87294-31-4
PY 2012
BP 697
EP 704
UT WOS:000318506500107
ER
PT J
AU Feitosa, LM
D'Souza, N
West, GD
Dong, HB
AF Feitosa, L. M.
D'Souza, N.
West, G. D.
Dong, H. B.
TI Solidification Reaction Sequence of Co-Rich Nb-Al-Co Alloys
SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND
MATERIALS SCIENCE
AB The freezing reaction sequence of Co-rich Nb-Al-Co ternary alloys with emphasis on the formation of Laves and Heusler phases has been examined. For Co-rich alloys, the solidification reaction sequence is observed as primary freezing of alpha-Co and CoAl phases, subsequent [Co + C36] and [CoAl + C36] eutectics, and the final ternary eutectic reaction [L -> alpha-Co + C36 + CoAl]. The compositions of solidified alpha-Co and C36 phases agree with the corresponding vertices of the tie-triangle at the solidus temperatures. When the Nb concentration is over 20 at. pct in Co-rich alloys, the quasi-peritectic reaction [L + Co2AlNb -> C36 + CoAl] does not occur as equilibrium prediction. The formation of C36 and CoAl phases occurs through solid precipitation and must be distinguished from a solidification reaction.
SN 1073-5623
EI 1543-1940
PD AUG
PY 2017
VL 48A
IS 8
BP 3814
EP 3822
DI 10.1007/s11661-017-4138-2
UT WOS:000404516100018
ER
PT J
AU Lawen, JL
Calabrese, SJ
Dinc, OS
AF Lawen, JL
Calabrese, SJ
Dinc, OS
TI Wear resistance of super alloys at elevated temperatures
SO JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME
CT 1997 World Tribology Congress
CY SEP 08-12, 1997
CL LONDON, ENGLAND
SP Soc Tribologists & Lubricat Engineers
AB This paper provides the results of an extensive sliding wear testing program to evaluate wear resistance of several material couples currently used for high temperature applications such as ground based gas turbines and aircraft engines. Nickel and cobalt base superalloys and iron base stainless steels were tested in different combinations, and their wear rates compared to determine optimal wear resistance. The results show that an alloy's wear resistance is highly dependent on operating temperature and its coupling with another material. The influences of friction, hardness, and oxide formation on the alloy's wear resistance are also presented and discussed.
SN 0742-4787
PD APR
PY 1998
VL 120
IS 2
BP 339
EP 344
DI 10.1115/1.2834432
UT WOS:000073130900030
ER
PT J
AU Montero, X
Galetz, MC
Schutze, M
AF Montero, X.
Galetz, M. C.
Schuetze, M.
TI Sulphidation Behavior of a Non Harmful Water-Based Al and Al-Si Slurry
Coating on CM247 Superalloy
SO OXIDATION OF METALS
AB Slurry aluminide coatings are widely applied to protect metallic surfaces from oxidation and corrosion. They are frequently used in gas turbine engine nozzles because of economical advantages and a straight-forward manufacturing route. A variety of commercial slurries are available to aluminize the surfaces of nickel-based superalloys, however, they have two main disadvantages. First, the phosphates and chromates or halides used as binders and to activate the diffusion species are environmentally harmful; second, the conventional systems have to be heat-treated in an inert atmosphere. As an outcome of the PARTICOAT project the variety of slurry derived coatings has been extended by tailoring the particle size of the metallic source. By doing that, environmentally friendly water-based slurries were developed to produce in a one-step process und atmospheric conditions, a thermal barrier system based on an aluminum diffusion layer and an alumina foam layer which serves as bond coat as well as top coat (TC). CM 247 nickel base superalloy was coated and heat-treated in air using newly developed Al and Al-Si slurries. The oxidation behavior was investigated at 1,000 A degrees C and then compared to pack-cemented aluminide coatings. The sulphidation behavior was investigated at 1,000 A degrees C in an atmosphere of 1.5 vol% SO2 in synthetic air for Al and Al-Si slurry coated samples with and without the alumina foam TC layer. PARTICOAT Al-based slurries,, after the initial stabilization of the TC, showed similar oxidation kinetics as pack cemented aluminides when exposed to air. When the coatings were exposed to sulphide-containing atmospheres, their oxidation rates increased, producing typical type I corrosion damage. Coatings without TC produced more protective oxide scales. The weight gain and coating area affected by corrosion were slightly lower for the Al-based slurries after 1,000 h of exposure than for the Al-Si based ones. The new coating presented here offers unique advantages in comparison to state-of-the-art slurry and pack cemented coatings by opening a potential way to manufacture a complete thermal barrier coating system by a simple, inexpensive and environmentally safe deposition and heat-treatment in air.
RI Schutze, Michael/Z-3655-2019
OI Galetz, Mathias/0000-0001-6847-2053
SN 0030-770X
EI 1573-4889
PD DEC
PY 2013
VL 80
IS 5-6
BP 635
EP 649
DI 10.1007/s11085-013-9412-0
UT WOS:000327081200017
ER
PT J
AU Chang, SH
Ko, CC
AF Chang, Shih-Hsien
Ko, Chih-Chien
TI Effects of MC Carbide Precipitates on the Microstructure and Mechanical
Properties of Cobalt-Based Alloys Adding TiC Powder via Vacuum Sintering
Process
SO MATERIALS TRANSACTIONS
AB In this study, different amounts of fine TiC powders (0, 10, 15 and 20 mass%) were mixed and added to cobalt-based alloy powders. Then, the mixed composite materials (cobalt-based alloy and TiC powders) were vacuum sintered at 1260, 1270, 1280 and 1290 degrees C for 1 h, respectively. The experimental results showed that the highest TRS value of 1485.1MPa was obtained by the addition of 15 mass% TiC powder and sintering at 1280 degrees C for 1 h; while the highest hardness value of HRA 80.4 was obtained by 20 mass% TiC powder sintered at 1290 degrees C for 1 h. In addition, two types of carbide precipitates appeared in the microstructure. Without added TiC powder of the specimen, fine plate-like precipitates of M6C and M23C6 carbides were obvious on the grain boundary; but when TiC powder was added to the specimens, only M23C6 carbides were observed after sintering treatment. The result also showed that a suitable amount of TiC additive (15 mass%) effectively inhibits carbide precipitation and growth.
SN 1345-9678
EI 1347-5320
PY 2013
VL 54
IS 3
BP 399
EP 404
DI 10.2320/matertrans.M2012299
UT WOS:000325703400022
ER
PT J
AU Cieslak, J
Tobola, J
Dubiel, SM
AF Cieslak, J.
Tobola, J.
Dubiel, S. M.
TI Site occupancies in sigma-phase Fe-Cr-X (X = Co, Ni) alloys:
Calculations versus experiment
SO COMPUTATIONAL MATERIALS SCIENCE
AB Ternary sigma-phase Fe-Cr-X (X = Co, Ni) alloys were studied theoretically (electronic structure calculations, Gibbs free energy analysis) and experimentally (X-ray diffraction, neutron diffraction, Mossbauer spectroscopy) in order to determine sublattice site occupancies by alloying elements. In general, good agreement between the predictions and experimental data was achieved. The obtained results agree reasonably well with expectations i.e. both Co and Ni atoms substitute for Fe atoms which predominantly occupy the sites A and D. (C) 2016 Elsevier B.V. All rights reserved.
RI Tobola, Janusz/N-7969-2017
OI Tobola, Janusz/0000-0003-3789-5701
SN 0927-0256
EI 1879-0801
PD SEP
PY 2016
VL 122
BP 229
EP 239
DI 10.1016/j.commatsci.2016.05.008
UT WOS:000378516900025
ER
PT J
AU Opris, CD
Liu, R
Yao, MX
Wu, XJ
AF Opris, C. D.
Liu, R.
Yao, M. X.
Wu, X. J.
TI Development of Stellite alloy composites with sintering/HIPing technique
for wear-resistant applications
SO MATERIALS & DESIGN
AB Cobalt-based superalloys, Stellite 694 and Stellite 712, composites were developed with the reinforcement of titanium-carbide particles for wear-resistant applications. The specimens were fabricated using the powder metallurgy technique, combined with hot isostatic pressing. Calorimetric effects of the alloy powders were investigated using the differential scanning calorimetry technique, which provided the theoretical basis of designing the sintering cycles. The phases formed in the microstructures were analyzed using the scanning electron microscope (SEM) and energy dispersive X-ray spectrum (EDS) techniques. The wear test was conducted on a ball-on-disc tribometer. It was demonstrated that the wear resistance of the alloys had been increased significantly by the titanium-carbide reinforcement and the hot isostatic pressing process had enhanced the wear resistance of the materials. (c) 2005 Elsevier Ltd. All rights reserved.
RI Abdelbary, A./K-7643-2013
OI Abdelbary, A./0000-0001-5581-9839
SN 0261-3069
PY 2007
VL 28
IS 2
BP 581
EP 591
DI 10.1016/j.matdes.2005.08.004
UT WOS:000242859100028
ER
PT J
AU CHANG, JC
ALLEN, SM
AF CHANG, JC
ALLEN, SM
TI ELASTIC ENERGY CHANGES ACCOMPANYING GAMMA-PRIME RAFTING IN NICKEL-BASE
SUPERALLOYS
SO JOURNAL OF MATERIALS RESEARCH
AB Eshelby's equivalent inclusion method is applied to the case of a single, inhomogeneous, ellipsoidal precipitate in an infinite matrix to study the morphological changes of the gamma-prime precipitates in nickel-base superalloys due to the influence of lattice constant misfit, elastic inhomogeneity and anisotropy, applied stress, and interfacial energy. The energy-minimizing inclusion shapes depend very sensitively on the degree of elastic inhomogeneity, on the sense and magnitude of the applied stress, and on the sense of the lattice constant misfit. The interfacial energy contribution can dominate that of elastic strain energy for small precipitate sizes, elastically compliant systems, nearly homogeneous alloys, and/or nearly isotropic materials. Calculations are carried out for two well-characterized nickel-base alloys: a Ni-13.5Al alloy (positive misfit, elastically hard inclusions) studied by Miyazaki et al. and CMSX-3 (negative misfit, elastically soft inclusions) studied by Pollock. The Eshelby energy calculations correctly predict the precipitate morphologies observed by Miyazaki et al. and by Pollock.
SN 0884-2914
PD SEP
PY 1991
VL 6
IS 9
BP 1843
EP 1855
DI 10.1557/JMR.1991.1843
UT WOS:A1991GF55000006
ER
PT J
AU Zielinska, M
Sieniawski, J
Wierzbinska, M
AF Zielinska, M.
Sieniawski, J.
Wierzbinska, M.
TI EFFECT OF MODIFICATION ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF
COBALT CASTING SUPERALLOY
SO ARCHIVES OF METALLURGY AND MATERIALS
AB Cobalt based heat - resisting superalloys are widely used for turbine blades and stationary elements of gas turbines (combustion space and stator blades) in acro-engines. These elements are generally produced by the investment casting method. The use of cobalt aluminate (CoAl2O4) for reducing relative;rain size of precision investment castings results in higher mechanical properties. The aim of the present work was settlement of basic physical and chemical properties of cobalt aluminate powder and its concentration in the interior surface of invested mould on the grain size and the microstructure, and in consequence, mechanical properties of high temperature creep resisting superalloy MAR M 509. For this purpose. file ceramic moulds were made with different kinds oh cobalt aluminate (manufactured by two different companies: Mason Color and Permedia Lublin) and its concentration in the primary slurry was from 0 to 10% mass. in zirconium flour. Stepped and cylindrical samples were casted for microstructure and mechanical examinations. The average grain size of the matrix (gamma phase). was determined on the stepped samples. The influence of surface modification on the grain size of tip to section thickness was considered. The microstructure investigations with the use of light microscopy and scanning electron microscopy (SEM) enable to examine the influence of the surface modification on the morphology of carbides precipitations. Verification of the influence of CoAl2O4 on the mechanical properties of castings were investigated on the basis of results obtained form tensile and creep tests.
RI Sieniawski, Jan/K-1108-2014
OI Sieniawski, Jan/0000-0002-5118-2743
SN 1733-3490
PY 2008
VL 53
IS 3
BP 887
EP 893
UT WOS:000260481200028
ER
PT J
AU WILLS, VA
MCCARTNEY, DG
AF WILLS, VA
MCCARTNEY, DG
TI A COMPARATIVE-STUDY OF SOLIDIFICATION FEATURES IN NICKEL-BASE
SUPERALLOYS - MICROSTRUCTURAL EVOLUTION AND MICROSEGREGATION
SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES
MICROSTRUCTURE AND PROCESSING
AB The solidification behaviour of four nickel-base superalloys has been studied using the technique of quenched directional solidification. Three of the alloys are designed for use as single crystals whereas the fourth, MAR-M002, is used in directionally solidified form. Freezing begins in all alloys with the formation of gamma-Ni dendrites and is terminated by a gamma + gamma' eutectic reaction. In MAR-M002, MC-type carbides form, with a Chinese-script morphology, in the interdendritic liquid behind the dendrite tips. Phase transformation temperatures were measured, together with the evolution of fraction solid with temperature. The behaviour of MAR-M002 is significantly more complex than that of the single-crystal alloys. Primary and secondary dendrite arm spacings correlate with solidification parameters and are relatively insensitive to alloy constitution. Measurements of elemental partitioning at the start of freezing show that aluminium, hafnium, molybdenum, tantalum and titanium always segregate to the liquid, cobalt and vanadium segregate to the dendrite core, and the segregation direction of chromium and tungsten depends on alloy constitution.
RI McCartney, David Graham/H-3274-2017
OI McCartney, David Graham/0000-0001-8608-9066
SN 0921-5093
PD OCT 15
PY 1991
VL 145
IS 2
BP 223
EP 232
DI 10.1016/0921-5093(91)90252-I
UT WOS:A1991GP10200011
ER
PT J
AU Potter, A
Sumner, J
Simms, NJ
AF Potter, A.
Sumner, J.
Simms, N. J.
TI The role of superalloy precipitates on the early stages of oxidation and
type II hot corrosion
SO MATERIALS AT HIGH TEMPERATURES
AB To meet materials challenges encountered in gas turbines, superalloys have been developed for high temperature, strength, oxidation and corrosion resistance. One strengthening method is using refractory metal additions to form carbide precipitates. However, such precipitates may be detrimental to the alloy's environmental resistance. This paper reports how refractory metal carbide precipitates affect the early stages of oxidation and hot corrosion of two alloys: Rene 80 (nickel-based) and MarM 509 (cobalt-based). Samples were exposed at 700 degrees C in either dry synthetic air or 90 ppm SOx , 10.5% CO2 , 8.5% O-2 5% H2O (balance N) with a 80/20 (Na/ K)(2) SO4 deposit (1.5 mu g/cm(2)/hour flux). The oxidation morphology and corrosion products were investigated by scanning electron microscope and energy dispersive X-ray analysis, to show that refractory metal carbide precipitates close to the metal surfaces disrupt protective oxide scale formation, thus providing inward transport routes for corrosive species.
OI Sumner, Joy/0000-0001-5435-200X
SN 0960-3409
EI 1878-6413
PY 2018
VL 35
IS 1-3
BP 236
EP 242
DI 10.1080/09603409.2017.1392413
UT WOS:000435483900026
ER
PT J
AU Yeh, AC
Chang, YJ
Tsai, CW
Wang, YC
Yeh, JW
Kuo, CM
AF Yeh, An-Chou
Chang, Yao-Jen
Tsai, Che-Wei
Wang, Yen-Chun
Yeh, Jien-Wei
Kuo, Chen-Ming
TI On the Solidification and Phase Stability of a Co-Cr-Fe-Ni-Ti
High-Entropy Alloy
SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND
MATERIALS SCIENCE
CT Symposium on High-Entropy Alloys
CY MAR 03-07, 2013
CL San Antonio, TX
AB In the present study, a Co1.5CrFeNi1.5Ti0.5 high-entropy alloy has been investigated for its high-temperature microstructural stability. This material is shown to possess mainly a face-centered cubic (FCC) structure; the eta phase is present at the interdendritic region in the as-cast condition, and it is stable between 1073 K and 1273 K (800 degrees C and 1000 degrees C); gamma' particles are found throughout the microstructures below 1073 K (800 degrees C). Segregation analysis has been conducted on a single crystal sample fabricated by a directional solidification process with a single crystal seed. Results show that Co, Cr, and Fe partition toward the dendritic region, while Ni and Ti partition toward the interdendritic areas. Scheil analysis indicates that the solid-liquid partitioning ratio of each element is very similar to those in typical single crystal superalloys. (C) The Minerals, Metals & Materials Society and ASM International 2013
RI Tsai, Che-Wei/S-2698-2019
OI Tsai, Che-Wei/0000-0003-3072-7916
SN 1073-5623
EI 1543-1940
PD JAN
PY 2014
VL 45A
IS 1
BP 184
EP 190
DI 10.1007/s11661-013-2097-9
UT WOS:000331092300025
ER
PT J
AU CLAVEL, AL
KASPERAN, JA
AF CLAVEL, AL
KASPERAN, JA
TI VAPOR-PHASE, FLUORIDE-ION PROCESSING OF JET ENGINE SUPERALLOY COMPONENTS
SO PLATING AND SURFACE FINISHING
AB Fluoride-ion cleaning, using hydrogen fluoride gas as the active agent, is rapidly becoming established as a cost-effective method of preparing nickel- and cobalt-based superalloys for braze repair in the aerospace industry.
Background and comparative information on the four basic processes currently in use are discussed. The latest process-using hydrogen fluoride gas directly-is described in detail, including the methods used for precise process control and safe handling of the HF input gas, as well as the off-gas fluoride compounds. Alloys successfully prepared for braze repair are listed. Other uses for the process and potential uses for the manufacture of new components are suggested.
SN 0360-3164
PD NOV
PY 1991
VL 78
IS 11
BP 52
EP 58
UT WOS:A1991GN37700012
ER
PT S
AU Moskal, G
AF Moskal, Grzegorz
BE Chandra, T
Wanderka, N
Reimers, W
Ionescu, M
TI Microstructure and thermal diffusivity of micro- and nano- sized YSZ
SO THERMEC 2009, PTS 1-4
SE Materials Science Forum
CT 6th International Conference on Processing and Manufacturing of Advanced
Materials
CY AUG 25-29, 2009
CL Berlin, GERMANY
SP Minerals, Met & Mat Soc
AB The thermal barrier coatings (TBC) enable to lower temperature (at approx. 170 degrees C) of operating elements in a hot section of gas turbine to a range, which enables to operate for a long time in conditions of high temperature influence and prolongs operation of them even three or four times. Usually, the TBC coverings are constructed of four layers:
superalloys on a base of nickel;
outer ceramic zone, from which low thermal conduction is required It is, in most cases, ZrO(2) oxide stabilized with Y(2)O(3) (YSZ yttria stabilized zirconia), material of one of lowest values of thermal conductivity in high temperature of a rank 2.3 Wm(-1)K(-1) in 1000 degrees C for 100% density and thermal expansion of a rank 11x10(-6)degrees C-1, what enables to reduce thermal stresses. Usually, thickness of an outer ceramic layer is within a range 250-375 mu m;
bond coat of a type Ni(Co)CrAlY or diffusion layer of a type (Ni,Pt)Al;
layer of barrier oxides, accrueting as a result of temperature growth TGO (thermally grown oxide).
In the present study characterization of conventional micro-sized YSZ powders stabilized by 8% of yttria and in comparison nano-sized YSZ will be presented. The tests performed showed that the monoclinic phase content in the nanocrystalline powder is approx. 8.8%, and approx 7.5% in the conventional powder. The chemical composition analysis and test of powder microstructure were also performed Carbon, sulphur and gas nitrogen contents were determined and the results received were similar The surface morphology and powder microstructure on the cross-sections were also characterized. The standard powder with spherical shape and relatively smooth surface is predominant. The internal structure is characterized by the presence of tiny sintered particles and low porosity. The nanocrystalline powder tests showed the presence of particles in the form of tiny polyhedrons with bimodal size distribution of particles (approx. 1 mu m and 10 mu m).
RI Moskal, Grzegorz/AAC-9033-2019; Moskal, G./F-9705-2010
OI Moskal, Grzegorz/0000-0001-7396-6568; Moskal, G./0000-0001-7396-6568
SN 0255-5476
PY 2010
VL 638-642
BP 900
EP 905
DI 10.4028/www.scientific.net/MSF.638-642.900
PN 1-4
UT WOS:000281043800148
ER
PT J
AU Aykut, S
Bagci, E
Kentli, A
Yazicioglu, O
AF Aykut, Seref
Bagci, Eyup
Kentli, Aykut
Yazicioglu, Osman
TI Experimental observation of tool wear, cutting forces and chip
morphology in face milling ofcobalt based super-alloy with physical
vapour deposition coated and uncoated tool
SO MATERIALS & DESIGN
AB Cobalt base superalloys are used extensively in applications requiring good wear, corrosion and heat resistance. The main goal of this study is to examine the effect of machining conditions (cutting speed, feed rate and depth of cut) on tool wear, chip morphology and cutting forces in symmetric face milling of cobalt base superalloy with physical vapour deposition coated and uncoated inserts. with the aim of achieving to achieve this goal, 90 milling experiments were carried out with different cutting speeds, feed rate and depth of cut under dry cutting conditions. The settings of machining parameters were determined by using general full factorial design method. Chip morphology, cutting forces and tool wear were compared by using PVD coated and uncoated hard metal inserts which are obtained dependent on feed rate, cutting speed and cutting depth. The cutting forces increase as the feed rate and depth of the cut increases, but cutting speeds' effect on cutting forces has not been observed for symmetric face milling. (C) 2006 Elsevier Ltd. All rights reserved.
RI Kentli, Aykut/V-9415-2017
OI Kentli, Aykut/0000-0002-4098-7220
SN 0261-3069
PY 2007
VL 28
IS 6
BP 1880
EP 1888
DI 10.1016/j.matdes.2006.04.014
UT WOS:000247786100016
ER
PT J
AU Hu, YF
Hao, WB
Deng, W
AF Hu Yifeng
Hao Wenbo
Deng Wen
TI Study on 3d-Shell Electrons and Bond Configuration in Ni-Co-Cr
Superalloys by Positron Annihilation Spectroscopy
SO RARE METAL MATERIALS AND ENGINEERING
AB Doppler-broadening spectra of positron annihilation radiation for pure metals Ni, Co and Cr and Ni-Co-Cr alloys with three different chemical compositions were measured by 2-detector coincidence technique. And the effect of the 3d electrons on Ni-Co-Cr alloy formation was analyzed. The results show that the 3d electron signal for the metal Ni is relatively higher among the three pure metals. The increase of Ni atom proportion in Ni-Co-Cr alloys leads to an increase in the probability of positron annihilation with free electrons. The experimental ratio curves for three Ni-Co-Cr alloys are greatly similar to the corresponding theoretic ratio curves, which indicate that the bonding nature in Ni-Co-Cr alloys is mainly metallic. This can explain why the Ni-Co-Cr alloys have good metal ductility.
SN 1002-185X
PD MAY
PY 2010
VL 39
IS 7
BP 1171
EP 1174
UT WOS:000280676400009
ER
PT J
AU Coskun, MB
Aksoy, S
Aksit, MF
AF Coskun, M. Bulut
Aksoy, Serdar
Aksit, Mahmut F.
TI Friction and Wear Characteristics of Haynes 25, 188, and 214 Superalloys
Against Hastelloy X up to 540 A degrees C
SO TRIBOLOGY LETTERS
AB As demand for more power increases, compression ratios, and operating temperatures keep rising. High speeds combined with high temperatures make turbomachinery sealing applications even more challenging. In order to confirm sufficient service life material pairs should be tested under conditions similar to engine operating conditions. This study presents high temperature friction and wear characteristics of cobalt/nickel superalloys, Haynes 25 (51Co-10Ni-20Cr-15W), Haynes 188 (39Co-22Ni-22Cr-14W), and Haynes 214 (75Ni-16Cr-3Fe-0.5Mn) sheets when rubbed against Hastelloy X (47Ni-22Cr-18Fe-9Mo) pins. Tests are conducted at 25, 200, 400, and 540 A degrees C with a validated custom design linear reciprocating tribometer. Sliding speed and sliding distance are 1 Hz and 1.2 km, respectively. Friction coefficients are calculated with friction force data acquired from a load cell. Wear coefficients are calculated through weight loss measurements. Results indicate that Haynes 25 (H25) has the lowest friction coefficients at all test temperatures. Above 400 A degrees C, H25 and Haynes 188 (H188) exhibit the best wear resistance. Protective cobalt oxide layers are formed on the H25 and H188 at 540 A degrees C in addition to nickel, chrome, and tungsten oxides. Although, it has better oxidation resistance, Haynes 214 has relatively higher wear rates than other tested materials especially at low temperatures. However, its wear performance improves beyond 200 A degrees C.
OI Coskun, M. Bulut/0000-0001-5349-6319
SN 1023-8883
EI 1573-2711
PD MAR
PY 2012
VL 45
IS 3
BP 497
EP 503
DI 10.1007/s11249-011-9912-5
UT WOS:000299506500013
ER
PT S
AU Konig, D
Pfetzing-Micklich, J
Frenzel, J
Ludwig, A
AF Koenig, Dennis
Pfetzing-Micklich, Janine
Frenzel, Jan
Ludwig, Alfred
BE Guedou, JY
Chone, J
TI Investigation of ternary subsystems of superalloys by thin-film
combinatorial synthesis and high-throughput analysis
SO EUROSUPERALLOYS 2014 - 2ND EUROPEAN SYMPOSIUM ON SUPERALLOYS AND THEIR
APPLICATIONS
SE MATEC Web of Conferences
CT 2nd European Symposium on Superalloys and their Applications
CY MAY 12-16, 2014
CL Giens, FRANCE
AB A Co-Ti-W thin film materials library was fabricated by magnetron sputtering. By using automated high-throughput measurement techniques (resistance mapping, automated XRD measurements) and cluster analysis a yet unknown phase region was revealed. The existence region of the new ternary phase is close to the composition Co60Ti15W25. In order to transfer the results from thin film to bulk material, a bulk sample was prepared by arc melting and subsequent heat treatment. Scanning electron microscopy and chemical micro-analysis data support that a yet unknown ternary phase exists in the system Co-Ti-W.
RI Ludwig, Alfred G/G-1111-2011; Pfetzing, Janine J/J-2412-2012
OI Ludwig, Alfred G/0000-0003-2802-6774; Pfetzing, Janine
J/0000-0003-0539-1146
SN 2261-236X
PY 2014
VL 14
AR 18002
DI 10.1051/matecconf/20141418002
UT WOS:000351930400069
ER
PT J
AU Decker, P
Naujoks, D
Langenkamper, D
Somsen, C
Ludwig, A
AF Decker, Peer
Naujoks, Dennis
Langenkaemper, Dennis
Somsen, Christoph
Ludwig, Alfred
TI High-Throughput Structural and Functional Characterization of the Thin
Film Materials System Ni-Co-Al
SO ACS COMBINATORIAL SCIENCE
AB High-throughput methods were used to investigate a Ni-Co-Al thin film materials library, which is of interest for structural and functional applications (superalloys, shape memory alloys). X-ray diffraction (XRD) measurements were performed to identify the phase regions of the N-Co-Al system in its state after annealing at 600 degrees C. Optical, electrical, and magneto optical measurements were performed to map functional properties and confirm XRD results. All results and literature data were used to propose a ternary thin film phase diagram of the Ni-Co-Al thin film system.
RI Ludwig, Alfred G/G-1111-2011
OI Ludwig, Alfred G/0000-0003-2802-6774; Decker, Peer/0000-0003-4323-3552;
Somsen, Christoph/0000-0002-0724-9111
SN 2156-8952
EI 2156-8944
PD OCT
PY 2017
VL 19
IS 10
BP 618
EP 624
DI 10.1021/acscombsci.6b00176
UT WOS:000412864700002
PM 28738146
ER
PT J
AU Girardot, J
Schneider, M
Berthe, L
Favier, V
AF Girardot, J.
Schneider, M.
Berthe, L.
Favier, V.
TI Investigation of delamination mechanisms during a laser drilling on a
cobalt-base superalloy
SO JOURNAL OF MATERIALS PROCESSING TECHNOLOGY
AB Temperatures in the high pressure chamber of aircraft engines are continuously increasing to improve the engine efficiency. As a result, constitutive materials such as cobalt and nickel-base superalloys need to be thermally protected. The first protection is a ceramic thermal barrier coating (TBC) cast on all the hot gas-exposed structure. The second protection is provided by a cool air layer realized by the use of a thousand of drills on the parts where a cool air is flowing through. The laser drilling process is used to realize these holes at acute angles. It has been shown on coated single crystal nickel-base superalloy that the laser drilling process causes an interfacial cracking (also called delamination), detected by a cross section observation. The present work aims at characterizing interfacial cracking induced by laser drilling on coated cobalt-base super alloy. On the one hand, this work attempted to quantify the crack by several microscopic observations with regards to the most significant process parameters related as the angle beam. On the other hand, we studied the difference of the laser/ceramic and the laser/substrate interaction with real time observation by using a fast movie camera. (c) 2013 The Authors. Published by Elsevier B.V. All rights reserved.
RI berthe, laurent J/E-6573-2010; Smith, Mark A/A-9053-2009; Berthe,
Laurent/W-8823-2019
OI Berthe, Laurent/0000-0002-9978-9843; GIRARDOT,
Jeremie/0000-0003-3690-6464; Schneider, Matthieu/0000-0002-5724-9937
SN 0924-0136
PD OCT
PY 2013
VL 213
IS 10
BP 1682
EP 1691
DI 10.1016/j.jmatprotec.2013.04.003
UT WOS:000321482700004
ER
PT J
AU Bardi, U
Carrafiello, L
Groppetti, R
Niccolai, F
Rizzi, G
Scrivani, A
Tedeschi, F
AF Bardi, U
Carrafiello, L
Groppetti, R
Niccolai, F
Rizzi, G
Scrivani, A
Tedeschi, F
TI On the surface preparation of nickel superalloys before CoNiCrAlY
deposition by thermal spray
SO SURFACE & COATINGS TECHNOLOGY
AB This work is dedicated to the study and the characterization of the surface of nickel superalloys before the deposition of the MCrAlY (M = Co, Ni or both) bond coat. Our aim is to determine the factors (roughness, contamination and others) that lead to the best properties of the coating in terms of adhesion. We used MAR M247 samples as substrates. Different preparation treatments were considered: dry and wet blasting by corundum with different grain size distribution, dry blasting by silicon carbide and cleaning by solid carbon dioxide. In general, we observed that the highest roughness led to the best adhesion as measured by critical load tests. However, this parameter must be balanced against known problems related to the use of coarse abrasive powders. (C) 2003 Elsevier B.V. All rights reserved.
RI Bardi, Ugo/L-1978-2015
OI Bardi, Ugo/0000-0003-2240-2070
SN 0257-8972
PD JUN 22
PY 2004
VL 184
IS 2-3
BP 156
EP 162
DI 10.1016/j.surfcoat.2003.10.135
UT WOS:000222044000005
ER
PT J
AU Zinkle, SJ
AF Zinkle, S. J.
TI Evaluation of high strength, high conductivity CuNiBe alloys for fusion
energy applications
SO JOURNAL OF NUCLEAR MATERIALS
CT Proceedings of the Sixth Symposium on Microstructural Processes in
Irradiated Materials (MPIM) Preface
CY MAR 03-07, 2013
CL San Antonio, TX
AB The unirradiated tensile properties for several different heats and thermomechanical treatment conditions of precipitation strengthened Hycon 3HPTM CuNiBe (Cu-2%Ni-0.35%Be in wt.%) have been measured over the temperature range of 20-500 C for longitudinal and long transverse orientations. The room temperature electrical conductivity has also been measured for several heats, and the precipitate microstructure was characterized using transmission electron microscopy. The CuNiBe alloys exhibit very good combination of strength and conductivity at room temperature, with yield strengths of 630-725 MPa and electrical conductivities of 65-72% International Annealed Copper Standard (IACS). The strength remained relatively high at all test temperatures, with yield strengths of 420-520 MPa at 500 degrees C. However, low levels of ductility (<5% uniform elongation) were observed at test temperatures above 200-250 C, due to flow localization near grain boundaries (exacerbated by having only 10-20 grains across the gage thickness of the miniaturized sheet tensile specimens). Scanning electron microscopy observation of the fracture surfaces found a transition from ductile transgranular to ductile intergranular fracture with increasing test temperature. Fission neutron irradiation to a dose of 0.7 displacements per atom (dpa) at temperatures between 100 and 240 degrees C produced a slight increase in strength and a significant decrease in ductility. The measured tensile elongation after irradiation increased with increasing irradiation temperature, with a uniform elongation of 3.3% observed at 240 degrees C. The electrical conductivity decreased slightly following irradiation, due to the presence of defect clusters and Ni, Zn, Co transmutation products. Considering also previously published fracture toughness data, this indicates that CuNiBe alloys have irradiated tensile and electrical properties comparable or superior to CuCrZr and oxide dispersion strengthened copper at temperatures <250 degrees C, and may be an attractive candidate for certain lowtemperature fusion energy structural applications. Conversely, CuNiBe may not be preferred at intermediate temperatures of 250-500 degrees C due to the poor ductility and fracture toughness of CuNiBe alloys at temperatures >250 degrees C. The potential deformation mechanisms responsible for the transition from transgranular to intergranular fracture are discussed. The possible implications for other precipitation-hardened alloys such as nickel based superalloys are briefly discussed. (C) 2013 Elsevier B.V. All rights reserved.
OI Zinkle, Steven/0000-0003-2890-6915
SN 0022-3115
EI 1873-4820
PD JUN
PY 2014
VL 449
IS 1-3
BP 277
EP 289
DI 10.1016/j.jnucmat.2013.09.007
UT WOS:000337018800035
ER
PT J
AU Liu, CB
Li, H
Lou, LH
AF Liu Chengbao
Li Hui
Lou Langhong
TI Isothermal Oxidation Behavior of Single-Crystal Nickel-Base Superalloy
DD10
SO RARE METAL MATERIALS AND ENGINEERING
AB The isothermal oxidation behaviors of two kinds of single-crystal nickel-base superalloys DD10 with different cobalt contents were investigated at 900, 1000 and 1100 degrees C in air by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy disperse X-ray analysis (EDX). It is found that increasing the cobalt content can decrease the diffusion activity energy of the alloy and thus increase the oxidation rate slightly. For the oxidation at 900 degrees C and 1000 degrees C, the mass gain basically obeys the parabola law. The oxide scales consist of three layers: an outer layer of Cr2O3 and TiO2, a thin intermediate layer of CrTaO4 and Ta2O5, and a continuous inner layer of Al2O3. For the oxidation at 1100 degrees C, because of the severe spalling of the scale and the volatilization of the CrO3, the kinetics curves deviate from the parabolic law a little. Some spinels such as NiCr2O4, CoAl2O4, CoNiO2 and Co2TiO4 form and inner nitridation phenomenon happens.
SN 1002-185X
PD AUG
PY 2010
VL 39
IS 8
BP 1407
EP 1410
UT WOS:000281904000019
ER
PT J
AU Azzam, A
Hauet, A
Danoix, F
Philippe, T
Sauvage, X
Blavette, D
AF Azzam, A.
Hauet, A.
Danoix, F.
Philippe, T.
Sauvage, X.
Blavette, D.
TI Phase transformations and gamma ' phase stability in model CoAlW
superalloys
SO JOURNAL OF ALLOYS AND COMPOUNDS
AB The present work aims at understanding the transformation mechanisms of gamma'-L1(2) precipitates in the ternary Co-Al-W system from quenched state to thermodynamic equilibrium. Three alloys with compositions Co-9Al-7W, Co-10Al-12W and Co-7Al-9W (at.%) were aged at 900 degrees C for 10 h, 200 h and 1000 h. The microstructure has been characterized by transmission and scanning electron microscopies, and the phase composition was determined using atom probe tomography. Results show that irrespective of the initial supersaturation, the quenched state is already decomposed into gamma+gamma'. This indicates that even in the Co-7Al-9W alloy that lies in the gamma+Co3W domain of the phase diagram, gamma' phase forms at first, indicating that gamma' is a metastable phase. In the two other alloys, during ageing at 900 degrees C gamma' phase dissolves and the equilibrium state is composed of gamma, CoAl and Co-3 W phases. The gamma' phase in the Co-7Al-9W alloy dissolves more rapidly compared to the two other alloys that are in the gamma+gamma' metastable domain. The volume fraction of Co3W phase increases rapidly with ageing time in the Co-7Al-9W alloy. Whereas gamma' phase is predominant at short ageing times, it becomes a minor phase after 1000 h of ageing, and is replaced mostly by the Co3W phase. As already observed, the transformation from gamma'-L1(2) to Co3W-D0(19) phase is taking place through a stacking fault. This mechanism occurs in the three alloys. In addition, a new dissolution mechanism interpreted as destabilization of the gamma' phase is evidenced in the Co-9Al-7W. The gamma' precipitates tend to split along {111} planes. Transmission electron microscopy investigations show that the dissolution and splitting mechanism of the gamma' phase is initiated by stacking faults, that are subsequently wetted by the gamma phase. (C) 2019 Elsevier B.V. All rights reserved.
SN 0925-8388
EI 1873-4669
PD AUG 25
PY 2019
VL 798
BP 832
EP 845
DI 10.1016/j.jallcom.2019.05.180
UT WOS:000471631300094
ER
PT J
AU Feng, Y
Wang, RC
Yu, K
Wen, DH
AF Feng Yan
Wang Richu
Yu Kun
Wen Danhua
TI Determination of isothermal sections of the Co-Nb-Ni and Ni-Mo-Re
ternary systems
SO RARE METALS
AB The isothermal sections of the Co-Nb-Ni ternary system at 1373 K and the Ni-Mo-Re ternary system at 1473 K were determined by means of diffusion triple and electron probe microanalysis (EPMA). The results indicate that there are three three-phase regions found in the Co-Nb-Ni ternary system at 1373 K: (Ni,Co) + NbCO3 + Ni3Nb, NbCO3 + NbCO2 + Ni3Nb, and NbCO2 + mu + Ni3Nb; and four three-phase regions found in the Ni-Mo-Re ternary system at 1473 K: Re + Ni + chi, Ni +NiMo + sigma, sigma + chi + Ni, and sigma + Mo + NiMo. No ternary compound is observed in the two isothermal sections. The isothermal sections are contrasted with the previous study.
SN 1001-0521
EI 1867-7185
PD FEB
PY 2008
VL 27
IS 1
BP 83
EP 88
DI 10.1016/S1001-0521(08)60036-4
UT WOS:000253782300019
ER
PT J
AU Ramirez, AL
Porcayo-Calderon, J
Mazur, Z
Salinas-Bravo, VM
Martinez-Gomez, L
AF Luna Ramirez, A.
Porcayo-Calderon, J.
Mazur, Z.
Salinas-Bravo, V. M.
Martinez-Gomez, L.
TI Microstructural Changes during High Temperature Service of a
Cobalt-Based Superalloy First Stage Nozzle
SO ADVANCES IN MATERIALS SCIENCE AND ENGINEERING
AB Superalloys are a group of alloys based on nickel, iron, or cobalt, which are used to operate at high temperatures (T > 540 degrees C) and in situations involving very high stresses like in gas turbines, particularly in the manufacture of blades, nozzles, combustors, and discs. Besides keeping its high resistance to temperatures which may approach 85% of their melting temperature, these materials have excellent corrosion resistance and oxidation. However, after long service, these components undergo mechanical and microstructural degradation; the latter is considered a major cause for replacement of the main components of gas turbines. After certain operating time, these components are very expensive to replace, so the microstructural analysis is an important tool to determine the mode of microstructure degradation, residual lifetime estimation, and operating temperature and most important to determine the method of rehabilitation for extending its life. Microstructural analysis can avoid catastrophic failures and optimize the operating mode of the turbine. A case study is presented in this paper.
RI PORCAYO-CALDERON, JESUS/I-7223-2016
OI PORCAYO-CALDERON, JESUS/0000-0002-6943-3926
SN 1687-8434
EI 1687-8442
PY 2016
AR 1745839
DI 10.1155/2016/1745839
UT WOS:000376312500001
ER
PT J
AU Zhou, ZM
Peng, H
Zheng, L
Guo, HB
Gong, SK
AF Zhou, Zimin
Peng, Hui
Zheng, Lei
Guo, Hongbo
Gong, Shengkai
TI Improved oxide scale adherence of low-Pt/Hf co-doped beta-NiAlCrSi
coating on superalloy IC21 at 1200 degrees C
SO CORROSION SCIENCE
AB Low-Pt/Hf co-doped beta-NiAlCrSi and Hf single-doped beta-NiAlCrSi coatings were produced onto advanced single crystal (SC) superalloy IC21 containing Mo, respectively. The cyclic oxidation and interdiffusion behaviour of the coatings at 1200 degrees C were investigated. As compared to the single-doped coating, the co-doped coating revealed suppressed interdiffusion and delayed beta-gamma' phase transformation. Simultaneously, the interfacial voids formation and scale rumpling were inhibited. As a result, the thermally grown oxide (TGO) grown on the co-doped coating exhibited improved adherence and the roles of Pt and Hf in low-Pt/Hf co-doped coating were discussed. (C) 2016 Elsevier Ltd. All rights reserved.
SN 0010-938X
EI 1879-0496
PD APR
PY 2016
VL 105
BP 78
EP 87
DI 10.1016/j.corsci.2016.01.005
UT WOS:000372760300009
ER
PT S
AU Peng, ZF
Cai, LS
Dang, YY
Zhao, L
Peng, FF
Yang, ZG
Yan, GZ
Chen, SG
Zhou, J
Zhou, YG
AF Peng, Zhifang
Cai, Lisheng
Dang, Yingying
Zhao, Lei
Peng, Fangfang
Yang, Zhigang
Yan, Guangzong
Chen, Shengguang
Zhou, Jun
Zhou, Yuangui
BE Chandra, T
Ionescu, M
Mantovani, D
TI A Brief Introduction to Alloy Phase Chemistry Determination under
EPMA/SEM-EDS Conditions and its Applications
SO THERMEC 2011, PTS 1-4
SE Materials Science Forum
CT 7th International Conference on Processing and Manufacturing of Advanced
Materials
CY AUG 01-05, 2011
CL Quebec City, CANADA
SP Minerals, Metals & Mat Soc
AB A so called multiphase separation method (MPSM) is proposed to quantitatively separate precipitated phases from their surrounding matrix phase in chemistry for bulk alloy/steel samples under EPMA/SEM-EDS measurement conditions. Applied examples to comparisons of the results through the MPSM with the values either cited or obtained via other analytical means relevant are indicative of the feasibility, accuracy as well as applicability of the MPSM, which deal with chemistry, amount, lattice parameter, elemental partitioning, atomic-site occupancy and stability of precipitated phases of either superalloy or heat-resistant steel samples analyzed. Successful applications of the MPSM not only show a significant improvement for difficulties in accurate quantification in phase chemistry under the EPMA/SEM-EDS measurement conditions but also provide with a useful and helpful tool to determine some other important physical quantities in alloys and steels, which make it possible to quantitatively and more widely evaluate structure-property relationships of the materials investigated through analyzing their bulk samples under EPMA/SEM-EDS measurement conditions.
SN 0255-5476
PY 2012
VL 706-709
BP 2450
EP +
DI 10.4028/www.scientific.net/MSF.706-709.2450
UT WOS:000308517301143
ER
PT J
AU Saldana, JM
Schulz, U
Rodriguez, GCM
Caceres-Diaz, LA
Lau, H
AF Munoz Saldana, J.
Schulz, U.
Mondragon Rodriguez, G. C.
Caceres-Diaz, L. A.
Lau, H.
TI Microstructure and lifetime of Hf or Zr doped sputtered NiAlCr bond
coat/7YSZ EB-PVD TBC systems
SO SURFACE & COATINGS TECHNOLOGY
AB NiAlCr-X overlay coatings deposited by magnetron sputtering on IN100 and CMSX-4 superalloys and thereafter top-coated with 7YSZ thermal barrier coatings by EB-PVD were investigated with emphasis on the effects of superalloy type and Hf or Zr doping. The sputtered films in the "as coated" condition (after EB-PVD deposition) showed strong diffusion effects of different elements from the superalloys. The measured phase content of beta and gamma' was in good agreement with calculated data obtained from experimental compositions normalized to a Ni-Al-Cr system following the guidelines of site preference of ternary alloying elements. Microstructure evolution and failure characteristics after furnace cyclic tests at 1100 degrees C were investigated as well. The lifetime of the coatings is equivalent to standard MCrAlY TBCs systems and is compared to PtAl and NiCoCrAlY coatings from literature. The effects of microstructure and elements diffusing from the substrates into the bond coat (Ti, Co, Mo and Ta) in combination with the effect of Hf- or Zr-doping is presented and discussed.
RI Munoz-Saldana, Juan/A-6391-2008; Saldana, Juan Munoz/AAD-1016-2019
OI Munoz-Saldana, Juan/0000-0001-5188-6305; Mondragon Rodriguez, Guillermo
Cesar/0000-0003-0328-1533
SN 0257-8972
PD FEB 15
PY 2018
VL 335
BP 41
EP 51
DI 10.1016/j.surfcoat.2017.12.017
UT WOS:000424720800005
ER
PT J
AU Bobzin, K
Brogelmann, T
Kalscheuer, C
Liang, T
AF Bobzin, K.
Broegelmann, T.
Kalscheuer, C.
Liang, T.
TI High temperature oxidation protection of gamma-titanium aluminide using
(Cr,Al) ON coatings deposited by high-speed physical vapor deposition
SO SURFACE & COATINGS TECHNOLOGY
CT 44th International Conference on Metallurgical Coatings and Thin Films
(ICMCTF)
CY APR 24-28, 2017
CL San Diego, CA
SP Amer Vacuum Soc, Sci & Technol Mat, Interfaces, & Proc, Adv Surface Engn Div
AB In recent years great efforts have been made in the development of gamma-TiAl alloys for use in aerospace applications such as turbines, where low densities and high temperature strength are required. However, gamma-TiAl alloys show poor oxidation resistance at temperatures T > 850 degrees C due to the formation of a non-protective oxide layer consisting of a mixture of TiO2 + Al2O3 in air, which could be easily spalled off, resulting in a shortened lifetime of the components. One promising way to overcome this problem is the deposition of an oxidation protective coating with low oxygen permeability at high temperatures. However, the interdiffusion between coating and substrate is still challenging even for advanced oxidation resistant coatings such as MCrAlY (M = Ni or Co) and aluminide. The present work focuses on the (Cr,Al)ON coating system, inspired from its outstanding diffusion barrier properties. Four (Cr,Al)ON coatings with different Cr:Al and N:O ratios were deposited onto gamma-TiAl substrate by the innovative High-Speed Physical Vapor Deposition (HS-PVD) technology, which enables the deposition of oxygen-rich coatings in a stable plasma process without target poisoning. Basing on hollow cathode discharge (HCD) and gas flow sputtering (GFS), the HS-PVD made it possible to deposit (Cr,Al)ON coatings at a deposition rate ds/dt > 16 mu m/h. The as-deposited coatings show an X-ray amorphous structure. Subsequently, the transmission electron microscopy (TEM) analysis confirmed the nanocomposite coating structure. The thermal stability and oxidation behavior of the coatings were evaluated by means of differential scanning calorimetry (DSC) and thermogravimetry (TGA) between T = 100 degrees C and T = 950 degrees C. It was confirmed that the Xray amorphous structure even remained stable at temperatures up to T = 950 degrees C. Moreover, cross-sectional SEM images of the coated samples after the HT-XRD measurements showed neither the formation of oxides at the coating substrate interface nor the interdiffusion of Ti into the coating, indicating a promising performance of the diffusion barrier. The results of the conducted research reveal a high potential of the HS-PVD deposited (Cr,Al)ON coatings for the oxidation protection of gamma-TiAl at T > 850 degrees C in turbine applications.
OI Liang, Tiancheng/0000-0003-2411-3539
SN 0257-8972
PD DEC 15
PY 2017
VL 332
BP 2
EP 11
DI 10.1016/j.surfcoat.2017.09.071
UT WOS:000418968100002
ER
PT J
AU Cloots, M
Kunze, K
Uggowitzer, PJ
Wegener, K
AF Cloots, Michael
Kunze, Karsten
Uggowitzer, Peter J.
Wegener, Konrad
TI Microstructural characteristics of the nickel-based alloy IN738LC and
the cobalt-based alloy Mar-M509 produced by selective laser melting
SO MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES
MICROSTRUCTURE AND PROCESSING
AB This study investigates selective laser melting (SLM) of the nickel based superalloy IN738LC and the cobalt based alloy Mar-M509, and identifies the influence of process and material parameters on the resulting microstructure. Comprehensive microstructural characterization was performed using electron backscattered diffraction analysis. Significant differences between IN738LC and Mar-M509 were observed with respect to grain size, grain shape and texture sharpness. Alloy IN738LC exhibits coarse and elongated grains with a sharp texture and thus a pronounced mechanical anisotropy. Alloy Mar-M509 shows smaller grains with only moderate structural and mechanical anisotropy. The different micro structural and mechanical characteristics are attributed to the different recovery and recrystallization behavior of IN738LC and Mar-M509. The high stacking fault energy (SFE) of IN738LC results in pronounced recovery of lattice defects without affecting the basic grain structure, whereas the low SFE in Mar-M509 favors recrystallization with the effect of significant grain refinement and weakening of the solidification texture. The effect of microstructure and the structural anisotropy on the orientation-dependent values of the Young's modulus and the mechanical properties are further discussed. (C) 2016 Elsevier B.V. All rights reserved.
RI Kunze, Karsten/B-8561-2013; Uggowitzer, Peter J/H-3581-2012
OI Kunze, Karsten/0000-0003-4682-8017; Uggowitzer, Peter
J/0000-0002-9504-5652; Cloots, Michael/0000-0002-6303-6938
SN 0921-5093
EI 1873-4936
PD MAR 21
PY 2016
VL 658
BP 68
EP 76
DI 10.1016/j.msea.2016.01.058
UT WOS:000372560800009
ER
PT J
AU Zheng, L
Xiao, CB
Zhang, GQ
Tang, X
Tang, DZ
AF Zheng Liang
Xiao Chengbo
Zhang Guoqing
Tang Xin
Tang Dingzhong
TI Solidification and Segregation Behavior of Cast Ni-Base Superalloy IN792
SO RARE METAL MATERIALS AND ENGINEERING
AB The solidification process of cast Ni-base superalloy IN792 was comparatively investigated by differential scanning calorimeter (DSC) and isothermal solidification quenching (ISQ) experiment. The distribution characteristics of elements in solidified solid and residual liquid at different temperatures were also concerned. The isothermal solidification microstructure, the phase precipitation diagram, the solidification characteristic curve and the segregation behavior of elements at different temperatures in liquidus and solidus range were obtained. The results of ISQ indicate that the IN792 alloy possesses a liquidus temperature of 1328 degrees C. The onset of MC carbides and eutectic (gamma+gamma') formation take place at 1310 and 1225 degrees C, respectively. The secondary gamma' is precipitated at 1190 degrees C. The macro-solidus temperature determined by DSC was 1250 degrees C. The volume fraction of residual liquid at this temperature can reach about 5%. The end of the solidification happened at 1180 degrees C, designated as micro-solidus temperature. No liquid remained at this temperature. There is a 70 degrees C gap between macro and micro-solidus temperature. The hot tearing tends to occur in this temperature range. About 85 vol% solid phase was formed within a range of 30 degrees C below the liquidus temperature. In 1300 similar to 1270 degrees C range, the residual liquid in the interdendritic region changed from connected channels to the isolated micro-liquid pools, which is related to the formation of micro-porosity defect. The distribution coefficient of element W and Co are more than 1, indicating that they tend to distribute in solid phase in dendritic region, which are negative segregation elements. The distribution coefficients of element Zr, Mo, Ti, Ta and Cr are less than 1, indicating that they tend to distribute in liquid phase in interdendritic region, which are positive segregation elements. The element Al tends to distribute to liquid phase at the beginning of the solidification, and then be prone to concentrate in the solid phase in the dendritic region and transform to a negative segregation element followed by the solidification temperature decreased. The distribution coefficient of element Al and Ni increases but Mo and Cr decreases followed by the solidification temperature decreasing in 1325 similar to 1210 degrees C range. On the contrary, The distribution of element Al and Ni decreases but Mo and Cr increases followed by the solidification temperature decreasing in 1210 similar to 1180 degrees C range.
OI Zheng, Liang/0000-0001-7090-0635
SN 1002-185X
PD AUG
PY 2012
VL 41
IS 8
BP 1457
EP 1462
UT WOS:000309019400031
ER
PT S
AU Gutmanas, EY
Gotman, I
AF Gutmanas, Elazar Y.
Gotman, Irina
BE Panin, VE
Psakhie, SG
Fomin, VM
TI Protective Coatings on Medical Implants by Reactive Diffusion
SO INTERNATIONAL CONFERENCE ON PHYSICAL MESOMECHANICS OF MULTILEVEL SYSTEMS
2014
SE AIP Conference Proceedings
CT International Conference on Physical Mesomechanics of Multilevel Systems
2014
CY SEP 03-05, 2014
CL Tomsk, RUSSIA
SP Inst Strength Phys & Mat Sci SB RAS, InstTheoret & Appl Mech SB RAS, Natl Res Tomsk Polytechn Univ, Natl Res Tomsk State Univ, Berlin Tech Univ, Techn Israel InstTechnol, Jozef Stefan Inst, Technol Platform Med Future, Technol Platform Light & Reliable Struct
AB Wear resistant and corrosion resistant surfaces are important for medical implants. Wear resistance is especially important for articulating surfaces in load bearing applications such as total hip and total knee replacements. Metal-on-polyethylene bearings result in relative large volumetric wear, ceramics such as alumina have an excellent wear resistance but are brittle, metal-on-metal bearings have good wear resistance, but release nanometric debris and ions that may cause allergy or have toxic effects. Hard ceramic coatings on metal substrates may be a good solution: low wear and low ion release and ductile metal alloy interior-no danger of brittle fracture and easy shaping. Ti alloys such as for example Ti-6Al-4 have the best combination of mechanical properties and biocompatibility, but have very poor wear resistance, Co-Cr-Mo have good wear resistance, but may cause allergy. TiN hard coatings deposited on Ti alloys by PVD have relatively poor adhesion to the substrate as a result limited durability. Hard coatings formed on the surface of Ti alloys, Zr as well as CoCrMo alloys by reactive diffusion have good adhesion to the substrate as a result of gradual change of composition and gradual change of hardness. Reactive diffusion coatings obtained employing developed Powder Immersion Reaction Assisted Coating (PIRAC) on articulating surfaces of Ti alloys and CoCrMo show excellent adhesion to the substrate. Total hip implants show good performance in wear simulator tests as well as in vivo tests in canine and rat models. The thickness of reactive diffusion coatings is proportional to square root from time. It is shown that that thicker TiN coatings can be obtained via 3 stage PIRAC process: nitriding followed by tiatanization and additional PIRAC nitriding. Similar approach in two stages-titanizaton followed by nitriding can be employed for processing on TiN based coatings on CoCrMo alloy. Duplex TiN coatin-TiN PIRAC coating followed by TiN plasma assisted PVD (PAPVD) results in thick coatings with excellent adhesion to the substrate. PIRAC titanization followed by was successfully used for conversion of Ni foam to NiTi Nitinol foam and formation of TiN coating on the surface of Nitinol foam, resulting in 10 fold decrease of Ni ions release into physiological solution. PIRAC nitriding was successfully used also for nitriding of TiNb alloys, Zr and Zr-2.5 Nb alloy. Two stage coating by wear resistant TiN based layer can be applied to steels, BCC metals such as Mo and W and Ni based superalloys.
SN 0094-243X
BN 978-0-7354-1260-6
PY 2014
VL 1623
BP 203
EP 208
DI 10.1063/1.4901481
UT WOS:000345971300051
ER
PT J
AU Aghaie-Khafri, M
Farahany, S
AF Aghaie-Khafri, M.
Farahany, S.
TI Creep Degradation of Thermally Exposed IN738C Superalloy
SO JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE
ASME
AB Creep degradation of an IN738C superalloy after long-term thermal exposure in an atmospheric furnace was investigated by means of accelerated creep tests. Experimental observation showed that the minimum creep rate increased by increasing the exposure time or exposure temperature and is a key factor for predicting creep life during long time, high temperature service. Concerning the exposure temperature and time, an empirical equation has been presented to estimate the creep lives of the pre-exposed specimens. Furthermore, the accuracy of the Monkman-Grant (Proceedings of ASTM, Vol. 56, pp. 593-620) relationship has been verified by experimental results.
RI Aghaie-Khafri, Mehrdad/B-2317-2012; Farahany, Saeed/K-3795-2015
OI Farahany, Saeed/0000-0002-1532-0416
SN 0742-4795
EI 1528-8919
PD MAY
PY 2009
VL 131
IS 3
AR 034501
DI 10.1115/1.3019056
UT WOS:000263526800029
ER
PT J
AU Naghavi, SS
Hegde, VI
Wolverton, C
AF Naghavi, S. Shahab
Hegde, Vinay I.
Wolverton, C.
TI Diffusion coefficients of transition metals in fcc cobalt
SO ACTA MATERIALIA
AB Using first-principles density functional theory (DFT), we calculate the diffusivities of 32 different solute elements all transition metals, together with Al and Si in fcc cobalt within the formalism of the five frequency model. For self-diffusion in fcc cobalt, we compare the accuracy of various approximations to the exchange-correlation energy functional of DFT in estimating the activation energy, and find that only the Perdew-Burke-Ernzerhof (PBE) approximation agrees well with experimental reports and all other functionals largely overestimate it. Our calculations also show that an accurate estimation of the self diffusion coefficient requires explicit calculation of the effective jump frequency and vacancy formation entropy via phonons. Using accurate self-diffusion data and scaling all solute-related attempt frequencies with respect to the attempt frequency for self-diffusion using a simple relation involving the atomic mass and melting temperature of the solute yields solute diffusivities in excellent agreement with experiments, where such data is available. We find that large solutes spontaneously relax toward the nearest neighbor vacancy to relieve the misfit strain, and the extent of this relaxation correlates negatively with the migration energy. Thus, in general, larger solutes have lower migration energies and diffuse faster than smaller solutes in fcc cobalt. However, extremely large solutes, e.g., group III elements Sc, Y, Lu, tend to be trapped in an energy valley located halfway toward the vacancy, and monovacancy mediated diffusion may no longer be valid in such cases. Finally, for all the solutes considered, we systematically tabulate the diffusion-related quantities calculated-diffusion prefactors, migration and activation energies constructing an extensive and accurate first-principles database for solute diffusion in fcc cobalt. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
RI Wolverton, Christopher/B-7542-2009; Ishwar Hegde, Vinay/I-4802-2012
OI Ishwar Hegde, Vinay/0000-0003-4786-823X
SN 1359-6454
EI 1873-2453
PD JUN 15
PY 2017
VL 132
BP 467
EP 478
DI 10.1016/j.actamat.2017.04.060
UT WOS:000405881500043
ER
PT J
AU Wang, CP
Qin, SY
Lu, Y
Yu, Y
Han, JJ
Liu, XJ
AF Wang, C. P.
Qin, S. Y.
Lu, Y.
Yu, Y.
Han, J. J.
Liu, X. J.
TI Interdiffusion and Atomic Mobilities in fcc Co-Cr-Mo Alloys
SO JOURNAL OF PHASE EQUILIBRIA AND DIFFUSION
AB The diffusion couples of Co-Cr-Mo ternary alloys were prepared and annealed at 1473 K for 72 h in order to determine the interdiffusion coefficients by using the electron probe microanalysis combined with Whittle and Green method. The experimental interdiffusion coefficients were critically assessed to the atomic mobilities by means of DICTRA software package. Good agreements were obtained from comprehensive comparison between the model-predicted diffusion properties and the experimental data, meanwhile, considered that the calculated diffusion coefficients were within the acceptable uncertainty of the experimentally measured diffusion coefficients, which verified the reliability of the atomic mobilities. The diffusion phenomena, such as diffusion paths and the concentration-distance profiles in the Co-Cr-Mo ternary system can be reasonably described by the presently obtained atomic mobilities.
OI Han, Jiajia/0000-0002-2642-0252
SN 1547-7037
EI 1863-7345
PD AUG
PY 2018
VL 39
IS 4
BP 437
EP 445
DI 10.1007/s11669-018-0657-9
UT WOS:000441127400008
ER
PT J
AU Balam, SSK
Dong, HQ
Laurila, T
Vuorinen, V
Paul, A
AF Balam, S. S. K.
Dong, H. Q.
Laurila, T.
Vuorinen, V.
Paul, A.
TI Diffusion and Growth of the mu Phase (Ni6Nb7) in the Ni-Nb System
SO METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND
MATERIALS SCIENCE
AB Incremental diffusion couple experiments are conducted to determine the average interdiffusion coefficient and the intrinsic diffusion coefficients of the species in the Ni6Nb7 (mu phase) in the Ni-Nb system. Further, the tracer diffusion coefficients are calculated from the knowledge of thermodynamic parameters. The diffusion rate of Ni is found to be higher than that of Nb, which indicates higher defect concentration in the Ni sublattice.
RI Laurila, Tomi/M-8058-2019; Laurila, Tomi T/B-2076-2013
OI Laurila, Tomi/0000-0002-1252-8764; Vuorinen, Vesa/0000-0002-0287-8832