The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Yuqing Weng - One of the best experts on this subject based on the ideXlab platform.
-
effect of microstructural evolution on high Temperature Strength of 9cr 3w 3co martensitic heat resistant steel under different aging conditions
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013Co-Authors: Yuqing WengAbstract:Abstract Evolution of microstructures and high-Temperature Strength at 650 °C of 9Cr–3W–3Co martensitic heat resistant steel after aging at 650 °C and 700 °C for different time durations have been experimentally investigated using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), field emission transmission electron microscopy (FETEM) and post-aged tensile tests. The results show that after aging at 650 °C, the high-Temperature Strength and the microstructures of 9Cr–3W–3Co steel keep almost stable with increasing aging time from 300 h to 3000 h. In comparison, after aging at 700 °C, there are obvious changes in the high-Temperature Strength and the microstructures. The Strengthening mechanisms of the 9Cr–3W–3Co steel were also discussed and the athermal yield stresses were calculated. The change of the high-Temperature Strength is mainly affected by the evolution of dislocations and laths. The precipitates mainly act as obstacles against motion of dislocations and lath boundaries.
-
Effect of microstructural evolution on high-Temperature Strength of 9Cr–3W–3Co martensitic heat resistant steel under different aging conditions
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2013Co-Authors: Yuqing WengAbstract:Abstract Evolution of microstructures and high-Temperature Strength at 650 °C of 9Cr–3W–3Co martensitic heat resistant steel after aging at 650 °C and 700 °C for different time durations have been experimentally investigated using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), field emission transmission electron microscopy (FETEM) and post-aged tensile tests. The results show that after aging at 650 °C, the high-Temperature Strength and the microstructures of 9Cr–3W–3Co steel keep almost stable with increasing aging time from 300 h to 3000 h. In comparison, after aging at 700 °C, there are obvious changes in the high-Temperature Strength and the microstructures. The Strengthening mechanisms of the 9Cr–3W–3Co steel were also discussed and the athermal yield stresses were calculated. The change of the high-Temperature Strength is mainly affected by the evolution of dislocations and laths. The precipitates mainly act as obstacles against motion of dislocations and lath boundaries.
K. Scott Weil - One of the best experts on this subject based on the ideXlab platform.
-
High Temperature Strength of YSZ joints brazed with palladium silver copper oxide filler metals
International Journal of Hydrogen Energy, 2011Co-Authors: Jens T. Darsell, K. Scott WeilAbstract:Abstract The Ag–CuOx system is being investigated as potential filler metals for use in air brazing high Temperature electrochemical devices such as solid oxide fuel cells and gas concentrators. The current study examines the effects of palladium addition on the high Temperature joint Strength of specimens prepared from yttria stabilized zirconia (YSZ) bars brazed with the binary Ag–CuOx, and 15Pd–Ag–CuO. It was found that while the binary Ag–CuOx system exhibits stronger room Temperature Strength than the 15Pd system the Strength is reduced to values equivalent of the 15Pd system at 800 °C. The 15Pd system exhibits a lower ambient Temperature Strength that is retained at 800 °C. In both systems the failure mechanism at high Temperature appears to be peeling of the noble metal component from the oxide phases and tearing through the noble metal phase whereas sufficient adhesion is retained at lower Temperatures to cause fracture of the YSZ substrate.
-
High Temperature Strength of YSZ joints brazed with palladium silver copper oxide filler metals
International Journal of Hydrogen Energy, 2011Co-Authors: Jens T. Darsell, K. Scott WeilAbstract:The Ag-CuOx system is being investigated as potential filler metals for use in air brazing high Temperature electrochemical devices such as solid oxide fuel cells and gas concentrators. The current study examines the effects of palladium addition on the high Temperature joint Strength of specimens prepared from yttria stabilized zirconia (YSZ) bars brazed with the binary Ag-CuOx, and 15Pd-Ag-CuO. It was found that while the binary Ag-CuOx system exhibits stronger room Temperature Strength than the 15Pd system the Strength is reduced to values equivalent of the 15Pd system at 800 °C. The 15Pd system exhibits a lower ambient Temperature Strength that is retained at 800 °C. In both systems the failure mechanism at high Temperature appears to be peeling of the noble metal component from the oxide phases and tearing through the noble metal phase whereas sufficient adhesion is retained at lower Temperatures to cause fracture of the YSZ substrate. © 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Jens T. Darsell - One of the best experts on this subject based on the ideXlab platform.
-
High Temperature Strength of YSZ joints brazed with palladium silver copper oxide filler metals
International Journal of Hydrogen Energy, 2011Co-Authors: Jens T. Darsell, K. Scott WeilAbstract:Abstract The Ag–CuOx system is being investigated as potential filler metals for use in air brazing high Temperature electrochemical devices such as solid oxide fuel cells and gas concentrators. The current study examines the effects of palladium addition on the high Temperature joint Strength of specimens prepared from yttria stabilized zirconia (YSZ) bars brazed with the binary Ag–CuOx, and 15Pd–Ag–CuO. It was found that while the binary Ag–CuOx system exhibits stronger room Temperature Strength than the 15Pd system the Strength is reduced to values equivalent of the 15Pd system at 800 °C. The 15Pd system exhibits a lower ambient Temperature Strength that is retained at 800 °C. In both systems the failure mechanism at high Temperature appears to be peeling of the noble metal component from the oxide phases and tearing through the noble metal phase whereas sufficient adhesion is retained at lower Temperatures to cause fracture of the YSZ substrate.
-
High Temperature Strength of YSZ joints brazed with palladium silver copper oxide filler metals
International Journal of Hydrogen Energy, 2011Co-Authors: Jens T. Darsell, K. Scott WeilAbstract:The Ag-CuOx system is being investigated as potential filler metals for use in air brazing high Temperature electrochemical devices such as solid oxide fuel cells and gas concentrators. The current study examines the effects of palladium addition on the high Temperature joint Strength of specimens prepared from yttria stabilized zirconia (YSZ) bars brazed with the binary Ag-CuOx, and 15Pd-Ag-CuO. It was found that while the binary Ag-CuOx system exhibits stronger room Temperature Strength than the 15Pd system the Strength is reduced to values equivalent of the 15Pd system at 800 °C. The 15Pd system exhibits a lower ambient Temperature Strength that is retained at 800 °C. In both systems the failure mechanism at high Temperature appears to be peeling of the noble metal component from the oxide phases and tearing through the noble metal phase whereas sufficient adhesion is retained at lower Temperatures to cause fracture of the YSZ substrate. © 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Tresa M. Pollock - One of the best experts on this subject based on the ideXlab platform.
-
High Temperature Strength of Co-based γ/γ' Superalloys
MRS Proceedings, 2020Co-Authors: Akane Suzuki, Garret C. Denolf, Tresa M. PollockAbstract:The high Temperature Strength of new Co-Al-W based alloys consisting of a ?-Co (fcc) matrix phase and a high volume fraction of ?'-Co3(Al, W) ternary L12 intermetallic compound has been examined in order to understand the Strengthening mechanisms and to explore the possibility for high Temperature applications. The flow stress exhibits a strong, positive dependence on Temperature above 873 K. Additions of Ta improve the high Temperature Strength, and the Strength of a Ta containing alloy is comparable to Ni-base superalloys at 1173 K. Transmission microscopy on the deformed Ta containing alloy revealed that the active slip modes within the ?' precipitates are {111} and {111} below and above the peak Temperature, respectively. At the peak flow Temperature, multiple slip modes including {111}, {001} and {111} were observed.
-
high Temperature Strength and deformation of γ γ two phase co al w base alloys
Acta Materialia, 2008Co-Authors: Akane Suzuki, Tresa M. PollockAbstract:Abstract The high-Temperature Strength and deformation behavior of γ/γ′ two-phase Co–Al–W-base alloys have been studied with polycrystalline and single-crystal materials. The ternary, quaternary and higher-order alloys containing Ta, Cr and/or Re exhibit flow stress anomalies above 873 K due to slip of pairs of 1/2〈1 1 0〉 superpartial dislocations on {0 0 1} planes, in addition to {1 1 1} planes, in the γ′ precipitates. Compression tests on the single-crystal specimens reveal a true anomalous peak Temperature of 1073 K for both ternary and Ta-containing quaternary alloys. Above the peak, the ternary alloy exhibits a rapid decrease in Strength with Temperature, as 1/2〈1 1 0〉 dislocations bypass the γ′ precipitates without significant shearing. Conversely, the Ta-containing quaternary alloy sustains Strength to higher Temperatures due to the activation of 1/3〈1 1 2〉 partial dislocation slip that introduces a high density of stacking faults in the γ′ precipitates.
Shuji Hanada - One of the best experts on this subject based on the ideXlab platform.
-
High Temperature Strength, fracture toughness and oxidation resistance of Nb–Si–Al–Ti multiphase alloys
Science and Technology of Advanced Materials, 2020Co-Authors: Yonosuke Murayama, Shuji HanadaAbstract:Abstract Nb–Si–Al–Ti quaternary phase diagram around three-phase region, which consists of niobium solid solution (Nbss), Nb3Al and Nb5Si3, is constructed in this study. The three-phase region exists up to titanium content of about 20 mol%. Based on the quaternary phase diagram, three-phase alloys containing Nbss from about 50 to 75% in volume are prepared to improve high Temperature Strength, room Temperature fracture toughness and oxidation resistance simultaneously. When microstructure and composition are optimized (Nbss+Nb3Al+Nb5Si3) three-phase alloy with the addition of titanium exhibits higher compressive Strength than nickel-based superalloys at room Temperature to 1573 K. Fracture toughness at room Temperature of (Nbss+Nb3Al+Nb5Si3) three-phase alloys is increased to over 12 MPa m1/2 by the addition of titanium without sacrificing high Temperature Strength. Oxidation resistance of (Nbss+Nb3Al+Nb5Si3) three-phase alloys is improved by the addition of titanium.
-
High-Temperature Strength of Directionally Solidified Al2O3/YAG/ZrO2 Eutectic Composite
Materials Science Forum, 2020Co-Authors: Yonosuke Murayama, Shuji Hanada, Akira Yoshikawa, Kazutoshi Shimizu, Narihito Nakagawa, Yoshikawa Waku, Tsuguo FukudaAbstract:A2O3/YAG/ZrO2 eutectic Melt-Growth-Composites (MGCs) were unidirectionally solidified by the modified-pulling-down method (MPD) and the Bridgman type method, in which a crucible was brought down at different speeds. The microstructures and crystallographic textures were studied by field emission scanning electron microscopy (FE-SEM) and electron backscattered pattern (EBSP) method. The high-Temperature Strength was investigated by compression tests. All MGC rods show strong preferred growing orientation, although the structural size of eutectic microstructure among MGC rods was different. The high-Temperature Strength of MGC rods is dependent on orientation, compression Temperature and strain rate. The high-Temperature Strength of MGC rods is controlled by the anisotropic Strength of constituent Al2O3, as well as the structural size of eutectic microstructure.
-
Texture Control and High-Temperature Strength of Directionally Solidified Al2O3/YAG/ZrO2 Eutectic Composite Rods
Materials Transactions, 2004Co-Authors: Yonosuke Murayama, Shuji Hanada, Akira Yoshikawa, Tsuguo FukudaAbstract:A 2 O 3 /YAG/ZrO 2 eutectic Melt-Growth-Composite (MGC) rods with two different microstructures were prepared by unidirectional solidification using the modified-pulling-down method (MPD) under different processing parameters. Microstructure and crystallographic texture were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and electron backscattered pattern (EBSP) method. High-Temperature Strength was evaluated by compression tests at 1773 K and 1873 K. Geometric pattern structure and Chinese script pattern structure are evolved by controlling processing parameters. MPD rods have strong preferred growing orientations in Al 2 O 3 of (001) for the geometric pattern structure and of (300) for Chinese script pastern structure. Constituent phases in the MPD rod hold the orientation relationship. The yield stress for the geometric pattern structure is over 1 GPa at 1773 K, which is extremely higher than that for Chinese script pattern structure. High-Temperature Strength at 1773 K and 1873 K depends on strain rate and Temperature in both the MPD rods.
-
High Temperature Strength of Nb3Al-base alloys
Intermetallics, 1998Co-Authors: Tatsuo Tabaru, Shuji HanadaAbstract:Abstract High Temperature Strength was investigated as a function of volume percent of Nb3Al using ternary alloys with controlled microstructures of equiaxed Nb3Al and Nbss (Nb solid solution) grains. Creep Strength was examined in Mo-added Nb3Al-base alloy with two types of different microstructures, equiaxed grains and directionally elongated grains. Mo addition increases high Temperature Strength at all the volume percents of Nb3Al, while Ta addition is effective only at high volume percents of Nb3Al. Ti addition decreases high Temperature Strength at all the volume percents of Nb3Al. Mo-added Nb3Al-base alloy consisting of directionally elongated grains has high creep Strength compared to other refractory intermetallic alloys such as MoSi2 alloy and ( Cr,Mo ) 3 Si ( Cr,Mo ) 5 Si 3 alloy. Creep Strength is decreased under a low applied stress in Mo-added Nb3Al-base alloy with equiaxed grains probably because of easy grain boundary sliding. The obtained results are discussed in terms of solid solution Strengthening of the constituent phases.
