BCC-Fe中1/2[111]刃型位错与[010]位错环相互作用的分子动力学研究

Molecular dynamics study of the interactions between the 1/2[111]edge dislocation and the[010]dislocation loop in BCC-Fe

研究压力容器(reactor pressure vessel, RPV)钢的辐照效应,需要从微观上揭示位错运动以及位错与辐照缺陷相互作用机理,从而为评估RPV钢在辐照作用下的宏观力学行为提供依据。该文采用分子动力学(molecular dynamics, MD)方法研究体心立方晶体(body center cubic, BCC)Fe中1/2[111]刃型位错与[010]位错环的相互作用,并分析了温度和位错环半径对相互作用过程以及临界剪切应力(critical resolved shearing stress, CRSS)的影响。结果表明:刃型位错与位错环相互作用包括混合位错段的形成、位错段的扫掠、螺旋偶极子的形成以及刃型位错挣脱位错环等过程;温度会促进位错环的吸收,并且刃型位错挣脱位错环所需的CRSS与温度有关,温度越高,CRSS越小。位错环半径越大,1/2[111]刃型位错扫掠的[010]位错段的长度越长,则临界剪切应力也就越大。

The mechanical behavior of irradiated RPV steel is important for nuclear reactor safety. The property changes are due to microscale dislocation motion and interactions between dislocations and irradiation defects that need to be further understood. This study used molecular dynamics studies to model the interactions between 1/2[111] edge dislocations and [010] dislocation loops in BCC-Fe. The models show the effects of temperature and dislocation loop radius on the interactions and the critical resolved shearing stress(CRSS). The results indicate that the interactions include the formation of mixed dislocation segments, sweeping of the dislocation segments, formation of screw dipoles and edge dislocations breaking away from the dislocation loop. Higher temperatures promote the absorption of dislocation loops and reduce the CRSS. The length of a [010] dislocation segment swept by 1/2[111] edge dislocation increases with increasing dislocation loop radius which increases the CRSS.