间隙原子非线性应力感生扩散的简化弹性偶极子模型

为了阐明体心立方晶体中外应力、位错应力和八面体间隙原子相互作用的本质,从理论上解释S-K弛豫和位错对Snoek弛豫的影响,提出一个简化的含有可动位错的一维弹性偶极子格点模型,讨论位错应力场中间隙原子的非线性应力感生扩散,为进一步对实际晶体的从头数值计算奠定基础。对一维模型的计算机模拟计算,表明位错应力场使得间隙原子形成具有非线性扩散特征的缺陷Fermi-Dirac分布,并增强了Snoek效应,在Snoek峰高温侧出现一个非线性扩散Snoek型内耗峰。 关键词：

SIMPLIFIED ELASTIC DIPOLE MODEL OF NONLINEAR STRESS-INDUCED DIFFUSION OF INTERSTITIALS

A simplified model of one dimensional elastic dipole discrete lattice containing oscillating dislocations is proposed to study the nonlinear stress-induced diffusion of interstitials in the inhomogeneous stress field of dislocation and to set up a foundation for further numerical calculation in real crystals, consequently, to clarify the interaction of the external stress, the dislocations and the octahedral interstitials in bcc crystals and to explain S-K relaxation and the effect of dislocation on Snoek relaxation theoretically. The simulation computation shows that the nonlinear diffusion of interstitials induced by the dislocation stress field makes the interstitials form a Fermi-Dirac distrubution of defects and enhances Snoek effect, hence, a peak of Snoek effect of nonlinear diffusion appears at higher temperature than that of Snoek peak.