刃型位错理论模型的实验验证

Experimental Validation of Edge Dislocation Theory Model

刃型位错芯周围变形场的实验测量是多年来非常困难的研究任务,它导致目前有多种位错理论模型并存。为了检验刃型位错理论模型的适用性,使用透射电子显微镜直接观察并获得了多晶金中刃型位错的高分辨电子显微图像,并采用几何相位分析方法测量了刃型位错周围的位移场和应变场。将实验测量结果与线弹性理论位错模型、Peierls-Nabarro位错模型及Fore-man(a=4)位错模型进行了比较。结果表明,三种位错理论模型在远离位错芯的区域都能描述刃型位错变形场,但在距离位错芯较近的区域,Peierls-Nabarro模型是最适当的位错理论模型。

Experimental measurement of deformation fields around the edge dislocation core is a very difficult research task over the years.It has led to the coexistence of several dislocation models.To validate the applicability of edge dislocation model,an edge dislocation in polycrystalline gold was observed directly by transmission electron microscope and high-resolution microscopy image of the edge dislocations was obtained successfully.Displacement fields and strain fields around the edge dislocation were mapped by geometric phase analysis method.Displacement and strain measurement results were compared with the isotropic elastic theory dislocation model,the Peierls-Nabarro dislocation model and the Foreman(a=4)dislocation model,respectively.Comparison results show that three theory models are all available for describing edge dislocation deformation field in the areas far from the dislocation core.But strain measurement shows a good agreement with Peierls-Nabarro dislocation model in the vicinity of dislocation core.