The Experts below are selected from a list of 1263 Experts worldwide ranked by ideXlab platform
Elizabeth A Holm - One of the best experts on this subject based on the ideXlab platform.
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applied machine learning to predict stress hotspots ii hexagonal close packed materials
International Journal of Plasticity, 2019Co-Authors: Ankita Mangal, Elizabeth A HolmAbstract:Abstract Stress hotspots are regions of stress concentrations that form under deformation in polycrystalline materials. We use a machine learning approach to study the effect of preferred Slip systems and microstructural features that reflect local crystallography, geometry, and connectivity on stress hotspot formation in hexagonal close packed materials under uniaxial tensile stress. We consider two cases: a hypothetical HCP material without any preferred Slip systems with a critically resolved shear stress (CRSS) ratio of 1:1:1, and a second with CRSS ratio 0.1:1:3 for basal: prismatic: Pyramidal Slip systems. Random forest based machine learning models predict hotspot formation with an AUC (area under curve) score of 0.82 for the Equal CRSS and 0.81 for the Unequal CRSS cases. The results show how data driven techniques can be utilized to predict hotspots as well as pinpoint the microstructural features causing stress hotspot formation in polycrystalline microstructures.
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applied machine learning to predict stress hotspots ii hexagonal close packed materials
arXiv: Materials Science, 2018Co-Authors: Ankita Mangal, Elizabeth A HolmAbstract:Stress hotspots are regions of stress concentrations that form under deformation in polycrystalline materials. We use a machine learning approach to study the effect of preferred Slip systems and microstructural features that reflect local crystallography, geometry, and connectivity on stress hotspot formation in hexagonal close packed materials under uniaxial tensile stress. We consider two cases: one without any preferred Slip systems with a critically resolved shear stress (CRSS) ratio of 1:1:1, and a second with CRSS ratio 0.1:1:3 for basal: prismatic: Pyramidal Slip systems. Random forest based machine learning models predict hotspot formation with an AUC (area under curve) score of 0.82 for the Equal CRSS and 0.81 for the Unequal CRSS cases. The results show how data driven techniques can be utilized to predict hotspots as well as pinpoint the microstructural features causing stress hotspot formation in polycrystalline microstructures
Haruyuki Inui - One of the best experts on this subject based on the ideXlab platform.
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plastic deformation of single crystals of ti5si3 with the hexagonal d88 structure
Acta Materialia, 2010Co-Authors: Kyosuke Kishida, Masakazu Fujiwara, Hiroki Adachi, K Tanaka, Haruyuki InuiAbstract:Abstract The deformation behavior of Ti 5 Si 3 single crystals with the hexagonal D8 8 structure has been investigated in compression as a function of crystal orientation in a temperature range from 1200 to 1500 °C. Three different types of deformation modes – { 1 1 ¯ 0 0 }[0 0 0 1] prismatic Slip, { 2 1 ¯ 1 ¯ 2 }1/3〈 2 1 ¯ 1 ¯ 3 ¯ 〉 Pyramidal Slip and { 2 1 ¯ 1 ¯ 8 }〈 8 4 ¯ 4 ¯ 3 ¯ 〉 twinning – were identified for the first time as being operative in Ti 5 Si 3 at temperatures above 1300 °C, depending on the loading axis orientation. The critical resolved shear stresses (CRSSs) decrease steeply with increasing temperature for all deformation modes. The values of the CRSSs for { 1 1 ¯ 0 0 }[0 0 0 1] prismatic Slip are considerably lower than those for { 2 1 ¯ 1 ¯ 2 }1/3〈 2 1 ¯ 1 ¯ 3 ¯ 〉 Pyramidal Slip, but are comparable to those for { 2 1 ¯ 1 ¯ 8 }〈 8 4 ¯ 4 ¯ 3 ¯ 〉 twinning. The favored deformation modes are discussed on the basis of anisotropic elasticity theory of dislocations.
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low temperature deformation of single crystals of a do19 compound with an off stoichiometric composition ti 36 5 at al
Philosophical Magazine, 1994Co-Authors: Haruyuki Inui, Y Toda, Yasuharu Shirai, M YamaguchiAbstract:Abstract Deformation behaviour of a DO19, compound with an off-stoichiometric composition of Ti-36·5 at.% Al has been studied as a function of orientation at temperatures from −196°C to room temperature in compression. The critical resolved shear stress (CRSS) for {1100} 〈11 20〉 prism Slip and (0001)〈1120〉 basal Slip increases with decreasing temperature. a dislocations introduced by prism Slip have a tendency to align along their screw orientation at −196°C, but the tendency becomes less marked with increasing temperature so that at room temperature these dislocations do not necessarily align along any particular crystallographic orientations. The CRSS for {1121} 〈1126〉 Pyramidal Slip shows a minimum in the CRSS-temperature curve at a temperature T min between −196 and −100°C. Most 2c + a dislocations are in screw orientation at temperatures below T min where the CRSS increases with decreasing temperature, whereas at temperatures above T min, where the CRSS anomalously increases with increasing temperatu...
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plastic deformation of single crystals of a do19 compound with an off stoichiometric composition ti 36 5 at al at room temperature
Philosophical Magazine, 1993Co-Authors: Haruyuki Inui, Y Toda, M YamaguchiAbstract:Abstract The deformation behaviour of single crystals of a DO19 compound with an off-stoichiometric composition of Ti-36·5 at.% Al has been studied at room temperature both in tension and compression. A tensile elongation as large as 250% has been observed for an orientation where prism Slip is fully operative, indicating that the compound is soft and quite deformable in single crystalline form for a certain orientation range. Tensile elongation is not sensitive to test environment and decreases with increasing strain rate. This indicates that the present compound is not susceptible to severe environmental embrittlement. For the basal Slip orientations, however, failure occurs soon after yielding even in compression due to the formation of deep shear cracks along basal Slip planes. Prism Slip obeys the Schmid's law and the critical resolved shear stress is considerably smaller than those for basal and Pyramidal Slip (one-third and one-ninth, respectively). Based on the results obtained, factors causing th...
Jaafar A Elawady - One of the best experts on this subject based on the ideXlab platform.
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effect of basal precipitates on extension twinning and Pyramidal Slip a micro mechanical and electron microscopy study of a mg al binary alloy
Acta Materialia, 2020Co-Authors: Quan Jiao, Laszlo J Kecskes, Jaafar A Elawady, Timothy P WeihsAbstract:Abstract Understanding the effects of basal precipitates on plasticity is of scientific interest and practical importance in the development of high-strength magnesium alloys. In this study, compression experiments are carried out on solution-treated and aged Mg–9wt.% Al binary alloy single-crystal micropillars cut from large-grained polycrystalline samples. The samples are compressed in two different orientations ( and ) to examine the effects of basal-precipitates on extension twinning and Pyramidal Slip, respectively. In the solution-treated, precipitate-free, samples, the propagation and thickening of single twins dominates, while in the aged micropillars with Mg17Al12 basal-precipitates, multiple twins are observed suggesting a substantial increase in the stress required to propagate and thicken twins compared to nucleating twins. In addition, these basal precipitates are observed to be more effective than c-axis rod precipitates in Mg-Zn alloy in impeding twin growth for the studied volume fractions. In samples, the plate-like, Mg17Al12 precipitates are found to provide enormous strengthening under compression, compared to solution-treated samples, by hindering the motion of Pyramidal dislocations. Further still, our comparative analysis suggests that Pyramidal-Slip/precipitate interactions, whether via bowing between or cutting precipitates, differ from one Mg alloy to another depending on the geometry and alignment of their precipitates. Our findings offer insights into how manipulating precipitation in the design and processing of Mg alloys can lead to superior mechanical properties.
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effect of basal precipitates on extension twinning and Pyramidal Slip a micro mechanical and electron microscopy study of a mg al binary alloy
Social Science Research Network, 2019Co-Authors: Quan Jiao, Laszlo J Kecskes, Jaafar A Elawady, Timothy P WeihsAbstract:Understanding the effects of basal precipitates on plasticity is of scientific interest and practical importance in the development of high-strength magnesium alloys. In this study, compression experiments are carried out on solution-treated and aged Mg-9wt.%Al binary alloy microcrystals pillars with two different compression orientations ( and ) to examine the effects of basal-precipitates on extension twinning and Pyramidal Slip, respectively. In the solution-treated, precipitate-free, samples, the propagation and thickening of single twins dominates, while in the aged microcrystals with Mg17Al12 basal-precipitates, multiple twins are observed suggesting a substantial increase in the stress required to propagate and thicken twins compared to nucleating twins. In addition, these basal precipitates are observed to be more effective than c-axis rod precipitates in impeding twin growth. In samples, the plate-like, Mg17Al12 precipitates are found to provide enormous strengthening under compression, compared to solution-treated samples, by hindering the motion of Pyramidal dislocations. Further still, our comparative analysis suggests that Pyramidal-Slip/precipitate interactions, whether via bowing between or cutting precipitates, differ from one Mg alloy to another depending on their precipitate characters. Our findings offer insights into how manipulating precipitation in the design and processing of magnesium alloys can lead to superior mechanical properties.
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towards resolving the anonymity of Pyramidal Slip in magnesium
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2015Co-Authors: Haidong Fan, Jaafar A ElawadyAbstract:Abstract Plasticity in magnesium crystals oriented for c -axis compression has been usually attributed to 〈 c + a 〉 dislo c ation Slip on second-order Pyramidal {11 2 ¯ 2} planes. Through molecular dynamics simulations, we investigated the formation and Slip characteristics of 〈 c + a 〉 dislocations on second-order Pyramidal planes. It is shown that the critical c -axis compressive stress for these dislocations is almost seven times that for 〈 c + a 〉 dislocations on first-order Pyramidal {10 1 ¯ 1} planes. In particular, it is concluded that first-order Pyramidal near-screw 〈 c + a 〉 dislocations play a predominant role during the c -axis compression of magnesium crystals. Careful reexaminations of published experimental observations show good agreements with the current predictions.
Timothy P Weihs - One of the best experts on this subject based on the ideXlab platform.
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effect of basal precipitates on extension twinning and Pyramidal Slip a micro mechanical and electron microscopy study of a mg al binary alloy
Acta Materialia, 2020Co-Authors: Quan Jiao, Laszlo J Kecskes, Jaafar A Elawady, Timothy P WeihsAbstract:Abstract Understanding the effects of basal precipitates on plasticity is of scientific interest and practical importance in the development of high-strength magnesium alloys. In this study, compression experiments are carried out on solution-treated and aged Mg–9wt.% Al binary alloy single-crystal micropillars cut from large-grained polycrystalline samples. The samples are compressed in two different orientations ( and ) to examine the effects of basal-precipitates on extension twinning and Pyramidal Slip, respectively. In the solution-treated, precipitate-free, samples, the propagation and thickening of single twins dominates, while in the aged micropillars with Mg17Al12 basal-precipitates, multiple twins are observed suggesting a substantial increase in the stress required to propagate and thicken twins compared to nucleating twins. In addition, these basal precipitates are observed to be more effective than c-axis rod precipitates in Mg-Zn alloy in impeding twin growth for the studied volume fractions. In samples, the plate-like, Mg17Al12 precipitates are found to provide enormous strengthening under compression, compared to solution-treated samples, by hindering the motion of Pyramidal dislocations. Further still, our comparative analysis suggests that Pyramidal-Slip/precipitate interactions, whether via bowing between or cutting precipitates, differ from one Mg alloy to another depending on the geometry and alignment of their precipitates. Our findings offer insights into how manipulating precipitation in the design and processing of Mg alloys can lead to superior mechanical properties.
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effect of basal precipitates on extension twinning and Pyramidal Slip a micro mechanical and electron microscopy study of a mg al binary alloy
Social Science Research Network, 2019Co-Authors: Quan Jiao, Laszlo J Kecskes, Jaafar A Elawady, Timothy P WeihsAbstract:Understanding the effects of basal precipitates on plasticity is of scientific interest and practical importance in the development of high-strength magnesium alloys. In this study, compression experiments are carried out on solution-treated and aged Mg-9wt.%Al binary alloy microcrystals pillars with two different compression orientations ( and ) to examine the effects of basal-precipitates on extension twinning and Pyramidal Slip, respectively. In the solution-treated, precipitate-free, samples, the propagation and thickening of single twins dominates, while in the aged microcrystals with Mg17Al12 basal-precipitates, multiple twins are observed suggesting a substantial increase in the stress required to propagate and thicken twins compared to nucleating twins. In addition, these basal precipitates are observed to be more effective than c-axis rod precipitates in impeding twin growth. In samples, the plate-like, Mg17Al12 precipitates are found to provide enormous strengthening under compression, compared to solution-treated samples, by hindering the motion of Pyramidal dislocations. Further still, our comparative analysis suggests that Pyramidal-Slip/precipitate interactions, whether via bowing between or cutting precipitates, differ from one Mg alloy to another depending on their precipitate characters. Our findings offer insights into how manipulating precipitation in the design and processing of magnesium alloys can lead to superior mechanical properties.
Edmund Tarleton - One of the best experts on this subject based on the ideXlab platform.
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tension compression asymmetry of c a Slip in ti 6al
Scripta Materialia, 2020Co-Authors: William Roberts, Jicheng Gong, Angus J. Wilkinson, Edmund TarletonAbstract:Abstract Microcantilevers with triangular cross-sections were machined using a focused ion beam from an α Ti–6Al alloy. Plasticity was predominantly in the lower part of the cantilever, allowing tension–compression asymmetry to be investigated by bending the cantilever up or down. Both ⟨a⟩ prismatic Slip and 〈 c + a 〉 Pyramidal Slip were investigated. The critical resolved shear stress was determined by calibrating a crystal plasticity model and found to be 329 MPa for ⟨a⟩ prismatic Slip in both tension and compression. However significant tension–compression asymmetry was observed for 〈 c + a 〉 Pyramidal Slip; increasing to 820 MPa under compression and decreasing to 558 MPa in tension.
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Tension–compression asymmetry of 〈c+a〉 Slip in Ti–6Al
Scripta Materialia, 2020Co-Authors: William Roberts, Jicheng Gong, Angus J. Wilkinson, Edmund TarletonAbstract:Abstract Microcantilevers with triangular cross-sections were machined using a focused ion beam from an α Ti–6Al alloy. Plasticity was predominantly in the lower part of the cantilever, allowing tension–compression asymmetry to be investigated by bending the cantilever up or down. Both ⟨a⟩ prismatic Slip and 〈 c + a 〉 Pyramidal Slip were investigated. The critical resolved shear stress was determined by calibrating a crystal plasticity model and found to be 329 MPa for ⟨a⟩ prismatic Slip in both tension and compression. However significant tension–compression asymmetry was observed for 〈 c + a 〉 Pyramidal Slip; increasing to 820 MPa under compression and decreasing to 558 MPa in tension.
