【作者】 万亮； 王绍青；

【Author】 WAN Liang,WANG Shao-qing (Shenyang National Laboratory for Materials Science,Institute of Metal Research,Chinese Academy of Sciences,Shenyang. 110016,China)

【机构】 中国科学院金属研究所沈阳材料科学国家(联合)实验室；

【摘要】 采用原子尺度计算模拟方法并结合嵌入原子型原子间相互作用势函数,对含∑9<1 10>{22 1}对称倾斜晶界的铜双晶体在纯剪切载荷作用下的形变行为进行了研究。能量最小化弛豫分析表明,该晶界存在两个能量局部极小的优化结构,其能量低者为稳态结构,另一能量稍高者为亚稳态结构。对双晶体在室温下的剪切过程进行分子动力学模拟发现,在不同取向的剪切载荷作用下,该晶界的结构转变模式有如下三种方式:(1)纯粹的晶界滑移;(2)晶界局部原子重排同时伴随晶界位错发射;(3)晶界滑移与晶界迁移相结合的耦合运动。结构演化分析表明,晶界耦合运动随剪切方向的不同有两种不同的方式:其一为由晶界原子集体运动而引起的结构单元转变过程;其二为由晶界局部原子重排过程引起的结构转变,这些局部原子重排过程互不关联。其中,前者会使晶界结构在稳态与亚稳态之间转化,而后者会引起晶界小面化。更多还原

【Abstract】 The deformation behavior of Cu bicrystals with theΣ9〈110〉{221} symmetric tilt grain boundary(STGB) under pure shear has been studied by atomistic simulation method with the embedded atom method(EAM) interatomic potentials.By using an energy minimization method,it shows that there are two optimized structures of this grain boundary (GB) which correspond to two local energy minima on the potential energy surface of the GB.The structure with lower energy is the stable one while the other is a metastable structure.The pure shear process of the bicrystals at ambient temperature has been studied by molecular dynamics(MD) simulation method.The simulated results indicate that there are three structure transformation modes of this GB depending on the shear direction:(1) pure GB sliding;(2) GB atomic shuffling accompanied by dislocation emission from GB;(3) GB migration coupled GB sliding,namely,GB coupling motion. In addition,an analysis of the structure evolution of the GB shows that,there are two mechanisms for GB coupling motion depending on the shear direction.One is the collective motion of GB atoms and the other is structure transformation realized by uncorrelated atomic shuffling processes.The former mechanism can induce structure transition of GB between the stable one and the metastable one,while the latter introduces faceting of the GB.更多还原