求晶体位错自能的离散弹性方案

考虑到晶体的离散点阵结构,滑移只能在原子之间进行,因此位错中心永远没有原子,位错中心附近分摊到每个原子的离散弹性能量处处有限。在刚性位错假定下,直接应用位错弹性理论解析结果,求出了晶体直奇异位错等效内切半径及其随位错中心位置的周期变化。对于简单四方晶体中奇异螺型位错,一级近似与Peierls模型结果巧合。计算了fcc和bcc两种晶系中各种位错的自能和等效位错内切半径,并初步考虑了各向异性弹性效应。结果表明:位错滑移面不是几何平面,bcc螺型位错滑移面类似于蜂巢结构。指出了用这种离散弹性方法进一步估算各种次级效应的可能。关键词：

A DISCRETE ELASTIC APPROACH FOR THE SELF-ENERGY OF THE CRYSTALLINE DISLOCATION

As the discrete lattice structure of crystal is considered, it is easy to see that slip can only take place between atoms, thus no atom is situated at the centre of dislocation exactly, the discrete elastic energy belongs to each atom near the centre of dislocation is limited everywhere. Under the assumption of rigid dislocation, using the analytical results of the elastic theory for dislocations directly, the inner cut radius of a singular crystalline dislocation and its periodic variation along with the position of dislocation centre are obtained. For the case of singular screw dislocation in simple orthogonal crystal, the first order approximation coincides with the result of Peierls model. The self energies and effective inner cut radii for two kinds of crystalline system (fcc and bcc) are calculated, and the effect of anisotropic elasticity is taken into account primarily.It is shown that the slip plane for a dislocation is not a geometric plane. The slip plane for the screw dislocation in bcc crystal looks like a bee nest.The possibility to further estimate some second ary effects by this discrete elasticity approach is pointed out.