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采用耦合应力的晶体相场法,研究纳米晶在单向拉伸过程中,大角度晶界和小角度晶界的运动,以及诱发晶体长大机制的联系。结果表明,在单向拉伸过程中,应力诱发了晶体长大,并且存在着晶界迁移和晶体转动两种机制,这两种机制相互影响联系。小角度晶界上位错的运动使得晶界消失,并引起晶体的转动而发生晶体合并,而大角度晶界表现为曲率诱发晶界运动,高能晶界逐渐消失,低能晶界生长;在晶界的迁移过程中,当晶粒尺寸足够小时,引发了晶体的转动,从而加快了晶体的长大。
The coupled phase-field method was used to study the motion of large-angle and small-angle grain boundaries and the mechanism of induced crystal growth during the uniaxial stretching of nanocrystals. The results show that during the uniaxial tensioning, the stress induces the growth of crystals, and there are two mechanisms of grain boundary migration and crystal rotation. These two mechanisms are mutually influential. The movement of dislocations at the small-angle grain boundaries causes the grain boundaries to disappear and causes the crystal to rotate and the crystal merges. However, the large-angle grain boundaries show curvature-induced grain boundary motions, the high-energy grain boundaries disappear and the low-energy grain boundaries grow. The migration process, when the grain size is small enough, triggered the rotation of the crystal, thereby speeding up the growth of the crystal.