Dislocation-mediated migration of interphase boundaries
来源期刊：JOURNAL OF MATERIALS SCIENCE TECHNOLOG2019年第11期
论文作者：Zhipeng Sun Fuzhi Dai Ben Xu Wenzheng Zhang
文章页码：2714 - 2726
摘 要：Faceted interphase boundaries（IPBs） are commonly observed in lath-shaped precipitates in alloys consisting of simple face-centred cubic（fcc）,body centred-cubic（bcc） or hexagonal closed packed（hcp）phases,which normally contain one or two sets of parallel dislocations.The influence of these dislocations on interface migration and possible accompanying long-range strain field remain unclear.To elucidate this,we carried out atomistic simulations to investigate the dislocation-mediated migration processes of IPBs in a pure-iron system.Our results show that the migration of these IPBs is accompanied with the slip of interfacial dislocations,even in high-index slip planes,with two migration modes were observed:the first mode is the uniform migration mode that occurs only when all of the dislocations slip in a common slip plane.A shear-coupled interface migration was observed for this mode.The other interfaces propagate in the stick-slip migration mode that occurs when the dislocations glide on different slip planes,involving dislocation reaction or tangling.A quantitative relationship was established to link the atomic displacements with the dislocation structure,slip plane,and interface normal.The macroscopic shear deformation due to the effect of overall atomic displacement shows a good agreement with the results obtained based on the phenomenological theory of martensite crystallography.Our findings have general implications for the understanding of phase transformations and the surface relief effect at the atomic scale.
Zhipeng Sun1，Fuzhi Dai2，Ben Xu1,3，Wenzheng Zhang1
1. School of Materials Science and Engineering,Tsinghua University2. Science and Technology of Advanced Functional Composite Laboratory,Aerospace Research Institute of Materials and Processing Technology3. Key Laboratory of Advanced Materials (MOE),State Key Laboratory of New Ceramics and Fine Processing
摘 要：Faceted interphase boundaries（IPBs） are commonly observed in lath-shaped precipitates in alloys consisting of simple face-centred cubic（fcc）,body centred-cubic（bcc） or hexagonal closed packed（hcp）phases,which normally contain one or two sets of parallel dislocations.The influence of these dislocations on interface migration and possible accompanying long-range strain field remain unclear.To elucidate this,we carried out atomistic simulations to investigate the dislocation-mediated migration processes of IPBs in a pure-iron system.Our results show that the migration of these IPBs is accompanied with the slip of interfacial dislocations,even in high-index slip planes,with two migration modes were observed:the first mode is the uniform migration mode that occurs only when all of the dislocations slip in a common slip plane.A shear-coupled interface migration was observed for this mode.The other interfaces propagate in the stick-slip migration mode that occurs when the dislocations glide on different slip planes,involving dislocation reaction or tangling.A quantitative relationship was established to link the atomic displacements with the dislocation structure,slip plane,and interface normal.The macroscopic shear deformation due to the effect of overall atomic displacement shows a good agreement with the results obtained based on the phenomenological theory of martensite crystallography.Our findings have general implications for the understanding of phase transformations and the surface relief effect at the atomic scale.
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