The Experts below are selected from a list of 75 Experts worldwide ranked by ideXlab platform
Andrew M. Minor - One of the best experts on this subject based on the ideXlab platform.
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in situ nanobeam electron diffraction strain mapping of planar slip in stainless steel
Scripta Materialia, 2018Co-Authors: Thomas C. Pekin, Christoph Gammer, Jim Ciston, Colin Ophus, Andrew M. MinorAbstract:Author(s): Pekin, TC; Gammer, C; Ciston, J; Ophus, C; Minor, AM | Abstract: © 2017 Nanobeam electron diffraction strain mapping has been used to measure the strain evolution in stainless steel under in situ deformation. As the amount of deformation increases, the Leading Dislocation of a planar slip band leaves behind a residual strain in the form of a small lattice expansion. Dislocation analysis confirmed that the Dislocations involved were l011 g type. While the characteristic residual strain of planar slip has often been observed, it has never before been directly measured. Our results provide a view into the dynamic mechanisms of planar slip, and showcase the possibilities of multidimensional in situ imaging.
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In situ nanobeam electron diffraction strain mapping of planar slip in stainless steel
Scripta Materialia, 2018Co-Authors: Thomas C. Pekin, Christoph Gammer, Jim Ciston, Colin Ophus, Andrew M. MinorAbstract:Abstract Nanobeam electron diffraction strain mapping has been used to measure the strain evolution in stainless steel under in situ deformation. As the amount of deformation increases, the Leading Dislocation of a planar slip band leaves behind a residual strain in the form of a small lattice expansion. Dislocation analysis confirmed that the Dislocations involved were type. While the characteristic residual strain of planar slip has often been observed, it has never before been directly measured. Our results provide a view into the dynamic mechanisms of planar slip, and showcase the possibilities of multidimensional in situ imaging.
Sukbong Kang - One of the best experts on this subject based on the ideXlab platform.
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Dislocation mechanism for dynamic recrystallization in twin-roll casting Mg-5.51Zn-0.49Zr magnesium alloy during hot compression at different strain rates
Transactions of Nonferrous Metals Society of China, 2016Co-Authors: Zhiyi Liu, Tiantian Huang, Wenjuan Liu, Sukbong KangAbstract:Abstract Dislocation mechanism operating in dynamic recrystallization (DRX) during hot compression of Mg–5.51Zn–0.49Zr alloy was investigated by X-ray diffraction, optical microscopy and transmission electron microscopy. The results showed that the continuous DRX occurred at a low strain rate of 1×10 −3 s −1 , which was associated with the operation of the single gliding Dislocation climbing. At the intermediate strain rate of 1×10 −2 s −1 , the continuous DRX was associated with the climbing of the gliding Dislocation array as deformed at an elevated temperature of 350 °C, and in contrast, the discontinuous DRX was observed and associated with the bulging of subgrain boundaries as the deformation temperature was raised to 400 °C. The continuous DRX was associated with the climbing of the Leading Dislocation ahead of pile-ups, and resultant rearrangement of misorientated flat Dislocation pile-ups as the strain rate was increased to 1×10 0 s −1 . It is suggested that the mechanism predominating the Dislocation climbing was changed from the vacancy migration to the stress acting on the Leading Dislocation ahead of the pile-up as the strain rate was gradually increased.
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low temperature dynamic recrystallization occurring at a high deformation temperature during hot compression of twin roll cast mg 5 51zn 0 49zr alloy
Scripta Materialia, 2009Co-Authors: Sukbong KangAbstract:Low-temperature dynamic recrystallization, which generally occurs below 200 °C, was found to occur at an elevated deformation temperature as high as 350 and 400 °C as the strain rate employed was increased up to 100 s−1 during hot compression of twin-roll-cast Mg–5.51Zn–0.49Zr (wt.%) alloy. New recrystallized grains formed at the junction of misorientated Dislocation pile-ups due to the rearrangement of the Dislocation pile-ups. Both the climbing force acting on the Leading Dislocation ahead of the pile-up and the free-energy change during this rearrangement were calculated.
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Low-temperature dynamic recrystallization occurring at a high deformation temperature during hot compression of twin-roll-cast Mg–5.51Zn–0.49Zr alloy
Scripta Materialia, 2009Co-Authors: Zhiyi Liu, Song Bai, Sukbong KangAbstract:Low-temperature dynamic recrystallization, which generally occurs below 200 °C, was found to occur at an elevated deformation temperature as high as 350 and 400 °C as the strain rate employed was increased up to 100 s−1 during hot compression of twin-roll-cast Mg–5.51Zn–0.49Zr (wt.%) alloy. New recrystallized grains formed at the junction of misorientated Dislocation pile-ups due to the rearrangement of the Dislocation pile-ups. Both the climbing force acting on the Leading Dislocation ahead of the pile-up and the free-energy change during this rearrangement were calculated.
Thomas C. Pekin - One of the best experts on this subject based on the ideXlab platform.
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in situ nanobeam electron diffraction strain mapping of planar slip in stainless steel
Scripta Materialia, 2018Co-Authors: Thomas C. Pekin, Christoph Gammer, Jim Ciston, Colin Ophus, Andrew M. MinorAbstract:Author(s): Pekin, TC; Gammer, C; Ciston, J; Ophus, C; Minor, AM | Abstract: © 2017 Nanobeam electron diffraction strain mapping has been used to measure the strain evolution in stainless steel under in situ deformation. As the amount of deformation increases, the Leading Dislocation of a planar slip band leaves behind a residual strain in the form of a small lattice expansion. Dislocation analysis confirmed that the Dislocations involved were l011 g type. While the characteristic residual strain of planar slip has often been observed, it has never before been directly measured. Our results provide a view into the dynamic mechanisms of planar slip, and showcase the possibilities of multidimensional in situ imaging.
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In situ nanobeam electron diffraction strain mapping of planar slip in stainless steel
Scripta Materialia, 2018Co-Authors: Thomas C. Pekin, Christoph Gammer, Jim Ciston, Colin Ophus, Andrew M. MinorAbstract:Abstract Nanobeam electron diffraction strain mapping has been used to measure the strain evolution in stainless steel under in situ deformation. As the amount of deformation increases, the Leading Dislocation of a planar slip band leaves behind a residual strain in the form of a small lattice expansion. Dislocation analysis confirmed that the Dislocations involved were type. While the characteristic residual strain of planar slip has often been observed, it has never before been directly measured. Our results provide a view into the dynamic mechanisms of planar slip, and showcase the possibilities of multidimensional in situ imaging.
Kyung-suk Kim - One of the best experts on this subject based on the ideXlab platform.
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Scale effects in friction of single–asperity contacts. II. Multiple–Dislocation–cooperated slip
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 1999Co-Authors: Juan A. Hurtado, Kyung-suk KimAbstract:In this paper we explore the second transition in the mechanism of frictional slip of single–asperity contacts, which takes place at large contact sizes. This is a transition from single–Dislocation–assisted (SDA) slip to multiple–Dislocation–cooperated (MDC) slip. It is found that the friction stress is controlled by Dislocation nucleation for SDA slip, and by Dislocation mobility for MDC slip. A model of concentric Dislocation loops is introduced to analyse Dislocation pile–up processes and their relationship to the friction stress. Dislocations are stabilized to be piled up as a result of the non–zero effective Peierls stress of the interface. The analysis shows that slip occurs when the condition for the nucleation of a new Dislocation and the condition for destabilizing the Leading Dislocation of the pile–up are simultaneously satisfied. It is also shown that, as the contact size increases, the friction stress approaches asymptotically a constant value equal to the effective Peierls stress of the interface. This result is in agreement with reported experimental results in the surface force apparatus (SFA). The case of a large number of Dislocations in the pile–up is studied via an asymptotic analysis, a key concept of which is the existence of a Dislocation–free zone that controls the Dislocation nucleation process. The analysis provides the connection between the discrete Dislocation model and the continuous cohesive zone model of single–asperity friction.
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scale effects in friction of single asperity contacts ii multiple Dislocation cooperated slip
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 1999Co-Authors: Juan A. Hurtado, Kyung-suk KimAbstract:In this paper we explore the second transition in the mechanism of frictional slip of single–asperity contacts, which takes place at large contact sizes. This is a transition from single–Dislocation–assisted (SDA) slip to multiple–Dislocation–cooperated (MDC) slip. It is found that the friction stress is controlled by Dislocation nucleation for SDA slip, and by Dislocation mobility for MDC slip. A model of concentric Dislocation loops is introduced to analyse Dislocation pile–up processes and their relationship to the friction stress. Dislocations are stabilized to be piled up as a result of the non–zero effective Peierls stress of the interface. The analysis shows that slip occurs when the condition for the nucleation of a new Dislocation and the condition for destabilizing the Leading Dislocation of the pile–up are simultaneously satisfied. It is also shown that, as the contact size increases, the friction stress approaches asymptotically a constant value equal to the effective Peierls stress of the interface. This result is in agreement with reported experimental results in the surface force apparatus (SFA). The case of a large number of Dislocations in the pile–up is studied via an asymptotic analysis, a key concept of which is the existence of a Dislocation–free zone that controls the Dislocation nucleation process. The analysis provides the connection between the discrete Dislocation model and the continuous cohesive zone model of single–asperity friction.
Juan A. Hurtado - One of the best experts on this subject based on the ideXlab platform.
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Scale effects in friction of single–asperity contacts. II. Multiple–Dislocation–cooperated slip
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 1999Co-Authors: Juan A. Hurtado, Kyung-suk KimAbstract:In this paper we explore the second transition in the mechanism of frictional slip of single–asperity contacts, which takes place at large contact sizes. This is a transition from single–Dislocation–assisted (SDA) slip to multiple–Dislocation–cooperated (MDC) slip. It is found that the friction stress is controlled by Dislocation nucleation for SDA slip, and by Dislocation mobility for MDC slip. A model of concentric Dislocation loops is introduced to analyse Dislocation pile–up processes and their relationship to the friction stress. Dislocations are stabilized to be piled up as a result of the non–zero effective Peierls stress of the interface. The analysis shows that slip occurs when the condition for the nucleation of a new Dislocation and the condition for destabilizing the Leading Dislocation of the pile–up are simultaneously satisfied. It is also shown that, as the contact size increases, the friction stress approaches asymptotically a constant value equal to the effective Peierls stress of the interface. This result is in agreement with reported experimental results in the surface force apparatus (SFA). The case of a large number of Dislocations in the pile–up is studied via an asymptotic analysis, a key concept of which is the existence of a Dislocation–free zone that controls the Dislocation nucleation process. The analysis provides the connection between the discrete Dislocation model and the continuous cohesive zone model of single–asperity friction.
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scale effects in friction of single asperity contacts ii multiple Dislocation cooperated slip
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 1999Co-Authors: Juan A. Hurtado, Kyung-suk KimAbstract:In this paper we explore the second transition in the mechanism of frictional slip of single–asperity contacts, which takes place at large contact sizes. This is a transition from single–Dislocation–assisted (SDA) slip to multiple–Dislocation–cooperated (MDC) slip. It is found that the friction stress is controlled by Dislocation nucleation for SDA slip, and by Dislocation mobility for MDC slip. A model of concentric Dislocation loops is introduced to analyse Dislocation pile–up processes and their relationship to the friction stress. Dislocations are stabilized to be piled up as a result of the non–zero effective Peierls stress of the interface. The analysis shows that slip occurs when the condition for the nucleation of a new Dislocation and the condition for destabilizing the Leading Dislocation of the pile–up are simultaneously satisfied. It is also shown that, as the contact size increases, the friction stress approaches asymptotically a constant value equal to the effective Peierls stress of the interface. This result is in agreement with reported experimental results in the surface force apparatus (SFA). The case of a large number of Dislocations in the pile–up is studied via an asymptotic analysis, a key concept of which is the existence of a Dislocation–free zone that controls the Dislocation nucleation process. The analysis provides the connection between the discrete Dislocation model and the continuous cohesive zone model of single–asperity friction.