Plastic Physics of Defect Mechanics

多晶延性材料的屈服可以通过位错跨晶界的转移来实现，或者通过残留的晶界位错与由于外加应力而在晶界附近形核的位错之间的结合来实现。这些现象是由GB周围的晶体取向和多轴应力状态决定的。在本研究中，利用由两个颗粒和一个GB组成的微柱，从纳米压痕的角度研究了几种缺陷相互作用中位错与GB的相互作用。此外，分子动力学模拟还揭示了均匀压缩和非均匀压痕应力状态下的物理位错反应，这些相互作用可以用本文提出的边界相互作用条件来概括。

Yielding of polycrystalline ductile materials can be realized by transfer of dislocation across a grain boundary (GB), or by incorporation between the residual GB dislocation and the dislocations nucleated in the near-field of GB due to the applied stress. These phenomena are determined by the crystallographic orientation and the multiaxial stress state around GB. In the present research, the interaction between dislocations and GB among several defects interactions has been investigated from nanoindentation using a micro-sized pillars consisting of two grains and one GB. Also molecular dynamics simulations revealed the physical dislocation reactions under a uniform compression and a nonuniform indentation stress state.These interactions can be summarized by using a boundary interaction condition proposed here.