The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Terence G Langdon - One of the best experts on this subject based on the ideXlab platform.
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developing superplasticity and a deformation Mechanism Map for the zn al eutectoid alloy processed by high pressure torsion
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: M Kawasaki, Terence G LangdonAbstract:Abstract A Zn–22% Al eutectoid alloy was processed by high-pressure torsion (HPT) for 1, 3 and 5 turns at room temperature to produce an ultrafine grain size of ∼350 nm. Tensile testing at a temperature of 473 K gave excellent superplastic properties with elongations to failure up to a maximum of 1800% at an imposed strain rate of 1.0 × 10 −1 s −1 : this is within the range of high strain rate superplasticity and represents the highest elongation recorded to date for a specimen processed by HPT. It is shown that the experimental data are in excellent agreement with a deformation Mechanism Map constructed for a temperature of 473 K.
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constructing a deformation Mechanism Map for a superplastic pb sn alloy processed by equal channel angular pressing
Scripta Materialia, 2009Co-Authors: Megumi Kawasaki, Terence G Langdon, Sangmok LeeAbstract:The Pb–62% Sn eutectic alloy was processed by equal-channel angular pressing and then tested in tension at a temperature of 413 K. The results show increasing superplastic elongations with decreasing strain rate including elongations up to >3000% at the lowest strain rate. A deformation Mechanism Map was plotted for the Pb–Sn alloy at a temperature of 413 K and it is shown that the experimental datum points are in excellent agreement with the predictions of the Map.
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the significance of grain boundary sliding in the superplastic zn 22 al alloy processed by ecap
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005Co-Authors: Terence G Langdon, Megumi KawasakiAbstract:A Zn–22 % Al eutectoid alloy was processed by equal-channel angular pressing (ECAP) to reduce the grain size to ~0.8 μm. Tensile testing at 473 K showed superplastic characteristics with a maximum elongation of ~2230 % at a strain rate of 1.0 × 10−2 s−1. The significance of grain boundary sliding (GBS) was evaluated by measuring sliding offsets at adjacent grains from the displacements of surface marker lines in samples pulled to elongations of 30 % at a series of different strain rates. The highest sliding contribution was recorded under testing conditions corresponding to the maximum superplastic ductility. There were relatively large offsets at the Zn–Zn and Zn–Al interfaces, but smaller offsets at the Al–Al interfaces. Analysis shows the results are affected by the presence of agglomerates of similar grains which are present after ECAP processing and specifically by the increased fraction of Al–Al boundaries. The experimental results are in excellent agreement with the predictions of a deformation Mechanism Map depicting the flow behavior in the Zn–22 % Al alloy, and the results confirm the importance of GBS as the dominant Mechanism of flow in superplasticity after processing by ECAP.
Winston O. Soboyejo - One of the best experts on this subject based on the ideXlab platform.
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microMechanisms of fatigue crack growth in a single crystal inconel 718 nickel based superalloy
Acta Materialia, 1999Co-Authors: C Mercer, Alfred B.o. Soboyejo, Winston O. SoboyejoAbstract:The fatigue crack growth behavior of an experimental, single crystal alloy, of equivalent nominal chemical composition to Inconel 718 is presented. Fracture modes under cyclic loading were determined by scanning electron microscopy. The results of the fractographic analyses are presented on a fracture Mechanism Map that shows the dependence of the fatigue fracture Mechanisms on the maximum stress intensity factor, K[sub max], and the stress intensity factor range, [Delta]K. Crack-tip deformation Mechanisms associated with fatigue crack growth were studied using transmission electron microscopy. The relative effects of [Delta]K and K[sub max] on the fatigue crack growth behavior of this material are discussed within the context of a two-parameter crack growth law. The influence of grain boundaries on the fatigue crack growth resistance of materials such as Inconel 718 is also discussed in light of the results of this investigation.
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MicroMechanisms of fatigue crack growth in a forged Inconel 718 nickel-based superalloy
Materials Science and Engineering A, 1999Co-Authors: C Mercer, Alfred B.o. Soboyejo, Winston O. SoboyejoAbstract:The microMechanisms of fatigue crack propagation in a forged, polycrystalline IN 718 nickel-based superalloy are evaluated. Fracture modes under cyclic loading were established by scanning electron microscopy analysis. The results of the fractographic analysis are presented on a fracture Mechanism Map that shows the dependence of fracture modes on the maximum stress intensity factor, K(max), and the stress intesity factor range, ΔK. Plastic deformation associated ith fatigue crack growth was studied using transmission electron microcopy. The effects of ΔK and K(max) on the Mechanisms of fatigue crack growth in this alloy are discussed within the context of a two-parameter crack growth law. Possible extensions to the Paris law are also proposed for crack growth in the near-threshold and high ΔK regimes.
C Mercer - One of the best experts on this subject based on the ideXlab platform.
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microMechanisms of fatigue crack growth in a single crystal inconel 718 nickel based superalloy
Acta Materialia, 1999Co-Authors: C Mercer, Alfred B.o. Soboyejo, Winston O. SoboyejoAbstract:The fatigue crack growth behavior of an experimental, single crystal alloy, of equivalent nominal chemical composition to Inconel 718 is presented. Fracture modes under cyclic loading were determined by scanning electron microscopy. The results of the fractographic analyses are presented on a fracture Mechanism Map that shows the dependence of the fatigue fracture Mechanisms on the maximum stress intensity factor, K[sub max], and the stress intensity factor range, [Delta]K. Crack-tip deformation Mechanisms associated with fatigue crack growth were studied using transmission electron microscopy. The relative effects of [Delta]K and K[sub max] on the fatigue crack growth behavior of this material are discussed within the context of a two-parameter crack growth law. The influence of grain boundaries on the fatigue crack growth resistance of materials such as Inconel 718 is also discussed in light of the results of this investigation.
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MicroMechanisms of fatigue crack growth in a forged Inconel 718 nickel-based superalloy
Materials Science and Engineering A, 1999Co-Authors: C Mercer, Alfred B.o. Soboyejo, Winston O. SoboyejoAbstract:The microMechanisms of fatigue crack propagation in a forged, polycrystalline IN 718 nickel-based superalloy are evaluated. Fracture modes under cyclic loading were established by scanning electron microscopy analysis. The results of the fractographic analysis are presented on a fracture Mechanism Map that shows the dependence of fracture modes on the maximum stress intensity factor, K(max), and the stress intesity factor range, ΔK. Plastic deformation associated ith fatigue crack growth was studied using transmission electron microcopy. The effects of ΔK and K(max) on the Mechanisms of fatigue crack growth in this alloy are discussed within the context of a two-parameter crack growth law. Possible extensions to the Paris law are also proposed for crack growth in the near-threshold and high ΔK regimes.
Megumi Kawasaki - One of the best experts on this subject based on the ideXlab platform.
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constructing a deformation Mechanism Map for a superplastic pb sn alloy processed by equal channel angular pressing
Scripta Materialia, 2009Co-Authors: Megumi Kawasaki, Terence G Langdon, Sangmok LeeAbstract:The Pb–62% Sn eutectic alloy was processed by equal-channel angular pressing and then tested in tension at a temperature of 413 K. The results show increasing superplastic elongations with decreasing strain rate including elongations up to >3000% at the lowest strain rate. A deformation Mechanism Map was plotted for the Pb–Sn alloy at a temperature of 413 K and it is shown that the experimental datum points are in excellent agreement with the predictions of the Map.
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the significance of grain boundary sliding in the superplastic zn 22 al alloy processed by ecap
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005Co-Authors: Terence G Langdon, Megumi KawasakiAbstract:A Zn–22 % Al eutectoid alloy was processed by equal-channel angular pressing (ECAP) to reduce the grain size to ~0.8 μm. Tensile testing at 473 K showed superplastic characteristics with a maximum elongation of ~2230 % at a strain rate of 1.0 × 10−2 s−1. The significance of grain boundary sliding (GBS) was evaluated by measuring sliding offsets at adjacent grains from the displacements of surface marker lines in samples pulled to elongations of 30 % at a series of different strain rates. The highest sliding contribution was recorded under testing conditions corresponding to the maximum superplastic ductility. There were relatively large offsets at the Zn–Zn and Zn–Al interfaces, but smaller offsets at the Al–Al interfaces. Analysis shows the results are affected by the presence of agglomerates of similar grains which are present after ECAP processing and specifically by the increased fraction of Al–Al boundaries. The experimental results are in excellent agreement with the predictions of a deformation Mechanism Map depicting the flow behavior in the Zn–22 % Al alloy, and the results confirm the importance of GBS as the dominant Mechanism of flow in superplasticity after processing by ECAP.
Alfred B.o. Soboyejo - One of the best experts on this subject based on the ideXlab platform.
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microMechanisms of fatigue crack growth in a single crystal inconel 718 nickel based superalloy
Acta Materialia, 1999Co-Authors: C Mercer, Alfred B.o. Soboyejo, Winston O. SoboyejoAbstract:The fatigue crack growth behavior of an experimental, single crystal alloy, of equivalent nominal chemical composition to Inconel 718 is presented. Fracture modes under cyclic loading were determined by scanning electron microscopy. The results of the fractographic analyses are presented on a fracture Mechanism Map that shows the dependence of the fatigue fracture Mechanisms on the maximum stress intensity factor, K[sub max], and the stress intensity factor range, [Delta]K. Crack-tip deformation Mechanisms associated with fatigue crack growth were studied using transmission electron microscopy. The relative effects of [Delta]K and K[sub max] on the fatigue crack growth behavior of this material are discussed within the context of a two-parameter crack growth law. The influence of grain boundaries on the fatigue crack growth resistance of materials such as Inconel 718 is also discussed in light of the results of this investigation.
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MicroMechanisms of fatigue crack growth in a forged Inconel 718 nickel-based superalloy
Materials Science and Engineering A, 1999Co-Authors: C Mercer, Alfred B.o. Soboyejo, Winston O. SoboyejoAbstract:The microMechanisms of fatigue crack propagation in a forged, polycrystalline IN 718 nickel-based superalloy are evaluated. Fracture modes under cyclic loading were established by scanning electron microscopy analysis. The results of the fractographic analysis are presented on a fracture Mechanism Map that shows the dependence of fracture modes on the maximum stress intensity factor, K(max), and the stress intesity factor range, ΔK. Plastic deformation associated ith fatigue crack growth was studied using transmission electron microcopy. The effects of ΔK and K(max) on the Mechanisms of fatigue crack growth in this alloy are discussed within the context of a two-parameter crack growth law. Possible extensions to the Paris law are also proposed for crack growth in the near-threshold and high ΔK regimes.