Sequence of deformation and cracking behaviours of Gallium–Arsenide during nano-scratching
Sequence of deformation and cracking behaviours of Gallium–Arsenide during nano-scratching
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DOI：
10.1016/j.matchemphys.2012.10.033
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发表时间：
2013-02
影响因子：
4.6
通讯作者：
K. Wasmer;M. Parlińska-Wojtan;S. Graça;J. Michler
中科院分区：
文献类型：
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作者：
K. Wasmer;M. Parlińska-Wojtan;S. Graça;J. Michler
GaAs {001}单晶在恒定的法向载荷（从5到100 mN）下使用布氏压头尖端进行划痕，压头的边缘平行于[110]方向以600 μm s-1的恒定速度移动。划痕过程产生塑性变形和各种类型的裂纹，例如中间裂纹、侧向裂纹和径向裂纹。第一次，已经实现了对塑性变形和开裂行为的不同步骤的理解。首先，局部位错云形成的表面下，并在压头的后半部分，其中的主剪应力是最大的。第二，中间裂纹是由表面下沿着（1 <$10）面聚集的位错堆积而成核的。随着压头继续增加应力，这些中值裂纹进一步扩展。同时，表面径向裂纹直接由压头尖端产生。然后，通过（111）平面中的塑性流动进行变形。第四，产生横向裂纹，然后由于位于横向裂纹的尖锐边缘处的高应力强度因子而形成径向裂纹。最后一个阶段是当横向或径向裂纹彼此相交时，大的切屑从表面脱落。除了塑性变形和开裂事件的顺序，它也表明，划痕深度，残留堆积，残留划痕深度和所有的裂纹遵循幂律依赖。最后，它被发现的弹性恢复是或多或少的15%，这是由所获得的流变因子X的值来解释。
GaAs {001} single crystals were scratched with constant normal loads (from 5 to 100 mN) using a Berkovich indenter tip with the edge moving parallel to the [110] direction with a constant velocity of 600 μm s−1. The scratching process generates both plastic deformation and various crack types, such as median, lateral and radial cracks. For the first time, an understanding of the different steps of the plastic deformation and cracking behaviour has been achieved. First, a localised dislocation cloud is formed below the surface and at the rear half of the indenter where the principal shear stress is maximal. Second, median cracks are nucleated by pile-up of converging dislocations below the surface along the (1¯10) plane. These median cracks propagate further as the indenter continues to increase the stress. Simultaneously, surface radial cracks are generated directly by the indenter tip. Then, deformation proceeds by plastic flow in the (111) plane. Fourth, lateral cracks are generated, and then radial cracks form off of these due to high stress intensity factor located at the sharp edges of the lateral cracks. The last phase is when lateral or radial cracks intercept each other, large chips are taken off from the surface. Apart from the sequence for the plastic deformation and cracking events, it is also demonstrated that the scratching depth, the residual pile-up, the residual scratch depth and all cracks follow a power-law dependence. Finally, it is found that the elastic recovery is more or less 15% which is explained by the value of the rheological factor X obtained.