含空洞双晶α-Fe中He团簇的分子动力学研究

Molecular Dynamics Study of Helium Cluster on Grain Boundary inα-Fe with Void

本文利用分子动力学方法和Gao等最近发现的Fe-He势函数研究了α-Fe倾侧晶界在300K下弛豫与单轴拉伸下He团簇的演变过程及材料内部空洞缺陷对He团簇的影响,并分析对比了拉伸过程中晶界的应力-应变曲线。结果显示:对比两种空洞位置,在弛豫过程中He原子更易在晶界面上的空洞中聚集发生He团簇;在拉伸加载阶段,晶界面空洞与晶界面相交处和基体内部空洞与晶界相切位置易产生微裂纹,成为断裂初始点。对比应力-应变曲线可知,其基体内部含有空洞时的双晶模型断裂应力及断裂应变最小。

The evolution of helium clusters during the annealing and tensile processing on the different tilt grain boundaries（GBs）at 300Kinα-Fe was studied applying atomistic simulation of Fe-He potentials developed by Gao,et al.,and the effect of the void defect to the helium clusters and the strength during the tensile were analyzed.The results show that the helium atoms are easier to gather to form helium clusters in the void on the grain boundary during the annealing and the micro cracks occur at the intersection of void and grain boundary and the tangent position between void in the bulk and grain boundary which are the fracture initiation points.Comparing the stress-strain curves,it is shown that the fracture stress and strain of the twin grain models in which the void is located in the bulk ofα-Fe are smallest.