取向角对小角度非对称倾斜晶界位错运动影响的晶体相场模拟  

Phase field crystal simulation of effect of misorientation angle on low-angle asymmetric tilt grain boundary dislocation motion

作　　者：祁科武 赵宇宏[1] 田晓林 彭敦维 孙远洋[1] 侯华[1] Qi Ke-Wu;Zhao Yu-Hong;Tian Xiao-Lin;Peng Dun-Wei;Sun Yuan-Yang;Hou Hua(Material Science and Engineering Institute,North University of China,Taiyuan 030051,China)

机构地区：[1]中北大学材料科学与工程学院,太原030051

出　　处：《物理学报》2020年第14期63-72,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51774254,51774253,51701187,51674226,51804279,51801189);山西省科技重大专项(批准号:20191102008);山西省平台基地和人才专项(批准号:201805D211036);中央引导地方科技发展专项资金(批准号:YDZX20191400002796);山西省科技成果转化引导专项(批准号:201804D131039)资助的课题.

摘　　要：采用晶体相场法模拟纳米尺度下小角度非对称倾斜晶界结构和位错运动,从外应力作用下晶界位错运动位置变化和晶体体系自由能变化角度,分析取向角对小角度非对称倾斜晶界结构和晶界位错运动的影响规律.研究表明,不同取向角下组成小角度非对称倾斜晶界的位错对类型相同.随取向角增大晶界位错对增加,且晶界更易形成n1n2型和n4n5型位错对.外应力作用下,不同取向角晶界位错对初始运动状态均沿晶界进行攀移运动,随体系能量积累,取向角越大出现晶界位错对分解的个数越多,且均为n1n2型和n4n5型位错对发生分解反应.不同取向角下小角度非对称倾斜晶界体系自由能曲线都存在四个阶段,分别对应位错对攀移、位错对滑移及分解、位错对反应抵消形成单晶和体系吸收能量自由能上升过程.进一步对比发现随取向角增大,晶界湮没形成的单晶体系所需时间增加.Grain boundary affects the microstructure of metal material,and thus further its macroscopic properties.As is well known,under the action of applied stress,the grain boundary migrates.The structures and arrangements of grain boundary dislocations at different misorientation angles are very different,which affects the macrophysical and chemical properties of metal crystal.Therefore,it is of great theoretical and practical significance to study the dislocation structure and reaction mechanism of grain boundary under different misorientations for further studying the material properties.The phase field crystal method is used to simulate the low-angle asymmetric tilt grain boundary structure and dislocation motion on a nanoscale.From the perspective of the change of the position of the grain boundary dislocation motion under the applied stress and the change of the free energy of the crystal system,the influences of the misorientation angle on the low-angle asymmetric tilt grain boundary structure and the motion of the grain boundary dislocation are analyzed.The results show that the types of dislocation pairs of low-angle asymmetric tilt grain boundaries at different misorientation angles are the same.With the increase of misorientation angle,the grain boundary dislocation pairs increase,and n1n2 and n4n5 type dislocation pairs are more easily formed at the grain boundaries.Under the action of applied stress,the initial movement states of the grain boundary dislocation pairs at different misorientation angles are all climbing along the grain boundaries.As the system energy accumulates,the larger the misorientation angle is,the more the number of decomposed grain boundary dislocation pairs decomposed will be,and only in the dislocation pairs of n1n2 and n4n5 type there occurs decomposition reaction.There are four stages in the free energy curve of the low-angle asymmetric tilt grain boundary system at different misorientation angles,which correspond to the dislocation pairs climbing,dislocation pairs sliding and deco

关 键 词：晶体相场 取向角 晶界 位错 

分 类 号：O772[理学—晶体学] TB383.1[一般工业技术—材料科学与工程]