表面效应对铁<100>间隙型位错环的影响

Surface effect on <100> interstitial dislocation loop in iron

在材料辐照损伤过程中,间隙型位错环的形成及动力学行为严重影响材料在辐照条件下的服役行为.在常用的以体心立方铁为基的合金材料中,1/2<111>和<100>是两种主要的位错环,其对辐照损伤的影响一直都是核材料领域研究的热点之一.在之前的研究中,人们对{111}面与单个1/2<111>位错环的相互作用进行了深入研究,发现表面对位错环性质确实有重要的影响.采用分子动力学方法,在原子尺度详细研究了另一个重要的表面铁{100}面对<100>间隙型位错环动力学过程的影响.模拟发现位错环伯格斯矢量与表面法线方向的关系、距表面的深度、位错环之间的相互作用以及温度等,都对位错环与表面的相互作用产生重要影响,其中,表面作用下的伯格斯矢量的演化以及<100>位错环在此过程中的一维运动首次被发现.基于这些模拟结果,就<100>位错环对表面辐照损伤结构的影响进行详细地研究,给出<100>位错环对表面凹凸结构的贡献,这些结果为理解辐照过程中材料表面的演化提供一种可能的解释.

Formation and evolution of interstitial dislocation loop induced by radiation damage in a material areconfirmed to seriously affect the performance of the material under irradiation. For example, in body-centeredcubic Fe based alloy, 1/2<111> and <100> are mainly formed during the irradiation, which is related to variousdegradations of material properties. Thus, the understanding of their effect on radiation damages of material isalways one of the hottest topics in nuclear material society. Previous studies have shown the surface effect on1/2 <111> loop through the investigation of the interaction between 1/2 <111> loop and {111} surface.Considering the difference in property between 1/2 <111> loop and <100> loop, in this work the interactionbetween a <100> loop and {100} surface is studied in detail through the molecular dynamics method. Thesimulation results indicate that the factors including Burgers vector of loop, loop-to-surface depth, interactionbetween pre-existing <100> loops, and temperature, all seriously affect the interaction between loop and surface.Especially, the present results show for the first time the evolution of Burgers vector of <100> loop from <100>to 1/2 <111> and its one-dimensional diffusion to surface. According to these results, we also further explore thesurface evolution after its interaction with loop. The appearance of atomic island results in the rugged surfacemorphology. All these results provide a new insight into the radiation damage to the surface of material.