Structural transformation and energy analysis for pile-up dislocations at triple junction of grain boundary  

晶界三叉处位错塞积的结构转变与能量分析

作　　者：Ying-jun GAO Zong-ji HUANG Qian-qian DENG Kun LIAO Yi-xuan LI Xiao-Ai YI Zhi-rong LUO 高英俊;黄宗吉;邓芊芊;廖坤;李依轩;易小爱;罗志荣(广西大学物理科学与工程技术学院,广西相对论天体物理重点实验室,广西先进能源材料重点实验室,南宁530004;玉林师范大学物理与电信工程学院,玉林537000)

机构地区：[1]Guangxi Key Laboratory of Advanced Energy Materials,Guangxi Key Laboratory for the Relativistic Astrophysics,School of Physics Science and Engineering,Guangxi University,Nanning 530004,China [2]School of Physics and Telecommunication Engineering,Yulin Normal University,Yulin 537000,China

出　　处：《Transactions of Nonferrous Metals Society of China》2022年第1期45-63,共19页中国有色金属学报（英文版）

基　　金：financial supports from the National Natural Science Foundation of China(Nos.51161003,51561031);the Natural Science Foundation of Guangxi,China(No.2018GXNSFAA138150)。

摘　　要：An energy model for the structure transformation of pile-ups of grain boundary dislocations(GBD)at the triple-junction of the grain boundary of ultrafine-grain materials was proposed.The energy of the pile-up of the GBD in the system was calculated by the energy model,the critical geometric and mechanical conditions for the structure transformation of head dislocation of the pile-up were analyzed,and the influence of the number density of the dislocations and the angle between Burgers vectors of two decomposed dislocations on the transformation mode of head dislocation was discussed.The results show when the GBD is accumulated at triple junction,the head dislocation of the GBD is decomposed into two Burgers vectors of these dislocations unless the angle between the two vectors is less than 90°,and the increase of applied external stress can reduce the energy barrier of the dislocation decomposition.The mechanism that the ultrafine-grained metal material has both high strength and plasticity owing to the structure transformation of the pile-up of the GBD at the triple junction of the grain boundary is revealed.提出超细晶材料的三叉晶界处晶界位错塞积的结构转变能量模型。运用该能量模型,计算体系的晶界位错塞积能量,分析塞积头位错的结构转变的临界几何条件和力学条件,讨论塞积位错的数密度和三叉晶界处的二个分解位错Burgers矢量之间的角度对头位错转变模式的影响。结果表明,当晶界位错在三叉晶界处塞积,只要这二个位错Burgers矢量夹角小于90°,头位错就能够分解为二个新的位错;外加应力的增加能够减少位错分解的阻力。另外,还揭示出超细晶材料同时具有高的强度和塑性的机理,归因于三叉晶界处的塞积位错的结构转变。

关 键 词：triple junction of grain boundary dislocation pile-up dislocation structural transformation energy model for pile-up ultrafine-grain materials 

分 类 号：TB30[一般工业技术—材料科学与工程]