Xu Lixia, Kong Lingqi, Zhao Hongwei, Wang Shunbo, Liu Sihan, Qian Long
School of Mechanical and Aerospace Engineering, Jilin University, 5988 RenMin Street, Changchun 130025, China.
Key Laboratory of CNC Equipment Reliability, Ministry of Education, Jilin University, 5988 RenMin Street, Changchun 130025, China.
Materials (Basel). 2019 Apr 11;12(7):1192. doi: 10.3390/ma12071192.
In this research, the mechanical behavior of undoped n-type GaAs was investigated by nanoindentation experiments using two types of indenters-Berkovich and flat-tip-with force applied up to 1000 mN. From the measured force-depth curves, an obvious pop-in phenomenon occurred at force of 150 mN with the flat-tip indenter representing elastic-plastic transition. The Young's modulus and hardness of GaAs were calculated to be 60-115 GPa and 6-10 GPa, respectively, under Berkovich indenter. Based on the observation of indent imprints, the fracture characteristics of GaAs were also discussed. A recovery of crack by the next indentation was observed at 1000 mN with Berkovich indenter. In the case of flat-tip indentation, however, surface material sank into a wing shape from 400 mN. In this sinking region, a density of fork-shaped sinking, slip lines, and crossed pits contributed to the slip bands, and converging crossed twinning deformations inside the GaAs material were generated. Since cracks and destructions on GaAs surface took place more easily under the flat-tip indentation than that of Berkovich, a machining tool with a sharp tip is recommended for the mechanical machining of brittle materials like GaAs.
在本研究中，通过使用两种压头——贝氏压头和平头压头——进行纳米压痕实验，研究了未掺杂n型砷化镓（GaAs）的力学行为，施加的力高达1000 mN。从测量的力-深度曲线来看，使用平头压头时，在150 mN的力处出现了明显的压入现象，这代表了弹塑性转变。在贝氏压头下，GaAs的杨氏模量和硬度分别计算为60 - 115 GPa和6 - 10 GPa。基于压痕印记的观察，还讨论了GaAs的断裂特性。使用贝氏压头在1000 mN时观察到下一次压痕使裂纹得到恢复。然而，在平头压痕的情况下，从400 mN起表面材料呈翼状下沉。在这个下沉区域，叉形下沉、滑移线和交叉坑的密度促成了滑移带，并在GaAs材料内部产生了汇聚的交叉孪晶变形。由于在平头压痕下GaAs表面比在贝氏压痕下更容易发生裂纹和破坏，因此对于像GaAs这样的脆性材料的机械加工，建议使用尖端锋利的加工工具。
