压痕诱发GaAs和Si晶体塑性、损伤与断裂

对压痕诱发脆性材料塑性、损伤与断裂研究进行总结, 并结合与之有关学科研究进展予以评述. 主要结果：微压痕诱导硅和砷化镓晶体的纳米和非晶转变, 并发现这一转变的临界应力; 转变过程是由切应力, 并非静水压力控制; 电子辐照诱导非晶晶化, 并发现晶化临界条件; 晶化速率与电流密度有关; 压痕诱发的裂纹尖端不是原子尖的, 其萌生与扩展伴随位错的产生, 并由此引发点阵的畸变, 并产生1～2nm宽非晶带； 裂纹扩展沿非晶带发生, 而非裂端前方原子键相继断裂的结果; 经傅立叶变换和逆变换发现, 裂纹尖端变形显示出各向异性.

Indentation-induced Plasticity, Damage and Fracture in Si and GaAs Single Crystals

Investigations of the plasticity, damage and fracture induced by micro-indentation are reviewed. The principal findings are: (a) Micro-indentation may induce a transition from crystalline to nano-crystalline and amorphous structure, and there is a critical stress for this kind of transition. The shear stress, rather than the hydrostatic stress is proposed to be attributed to this transition. (b) There is a critical current density for the crystalline nucleation, and it is no related to the irradiation-induced temperature rise. (c) The crack-tip produced dislocations by during indentation is not atomically sharp, leading to crystal lattice distortion, and even to a transition from a crystalline lattice to disordered structure. An amorphous band with a width of 1-2nm between crack-walls is formed, and the crack propagation is then along the amorphous band, rather than sequential rupture of the cohesive bonds. (d) Fast Fourier Transformation (FFT)-SAED and corresponding Inverse-Fast Fourier Transformation (IFFT) fringe images from different lattice planes in selected areas of the crack-tip show that deformation around the crack-tip deformation is anisotropic.