晶体相场法研究小角晶界<100>位错芯的扩展演化

Study on the Extension and Evolution of 〈100〉 Dislocation Core at Small Angle Grain Boundaries by Phase Field Crystal Model

关键词:  晶体相场法  <100>位错芯  小角晶界  位错反应  应变场

Key words:  Phase Field Crystal method  〈100〉 dislocation core  small angle grain boundary  dislocation reaction  strain field

摘要:

位错扩展对材料的性能有重要影响。本文应用晶体相场(PFC)法模拟体心立方(BCC)晶体的双晶晶界在施加双轴应变下，晶界的<100>位错芯的扩展现象。研究发现，晶界的<1-00>位错芯区域出现空位，从而给位错芯的扩展提供了条件。研究表明：随着应变量的增加，<100>位错发生分解反应，位错芯从单个刃位错分解成两个混合位错，然后，两个相邻的位错芯扩展成一个整体。这个大位错芯里包括4个柏氏矢量不同的1/2<111>位错，晶界的<100>位错的分解反应与这个1/2<111>位错相关，应变场分析表明<100>位错芯扩展时出现应变集中。

Abstract:

Dislocation propagation has an important influence on the properties of materials.In this article,Phase Field Crystal (PFC) method is used to simulate the extension of 〈100〉 dislocation cores in the grain boundary of Body Centered Cubic (BCC) crystal when biaxial strain is applied to the two grain boundary. It is found that there are vacancies in the 〈1-00〉 dislocation core region of the grain boundary,thus providing conditions for the extension of dislocation cores.The research shows that with the increase of strain,〈100〉dislocations undergo decomposition reaction.The dislocation core is decomposed from a single edge dislocation into two mixed dislocations,and then two adjacent dislocation cores develop into a whole.This large dislocation core contains four 1/2〈111〉 with different Burgers vectors.The decomposition reaction of 〈100〉 dislocation at the grain boundary is related to this dislocation 1/2〈111〉.The strain field analysis shows that the strain concentration occurs when the 〈100〉 dislocation core develops.