Nanoindentation and nanoscratch tests of YAG single crystals: An investigation into mechanical properties, surface formation characteristic, and theoretical model of edge-breaking size
Nanoindentation and nanoscratch tests of YAG single crystals: An investigation into mechanical properties, surface formation characteristic, and theoretical model of edge-breaking size
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YAG单晶的纳米压痕和纳米划痕测试：机械性能、表面形成特性和边缘断裂尺寸理论模型的研究
DOI：
10.1016/j.ceramint.2019.10.048
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发表时间：
2020-02-15
影响因子：
5.2
通讯作者：
Dong, Guojun
中科院分区：
文献类型：
--
作者：
Li, Chen;Zhang, Qiang;Dong, Guojun
系统地进行了YAG单晶的纳米压痕和纳米划痕实验。通过纳米压痕试验获得了YAG单晶的弹性回复率、弹性模量、纳米硬度和断裂韧性等力学性能。用扫描电镜分析了划痕沟槽的表面形貌。不同深度纳米划痕诱导YAG单晶的形成特征表明，在划痕过程中存在明显的脆性向韧性转变现象。YAG单晶脆性去除主要发生在表面径向裂纹先于断边现象，横向裂纹向工作材料表面延伸。建立了考虑应力强度因子、弹性回复率和残余力的纳米划痕断边尺寸理论模型。该模型表明，边断尺寸随法向力、平均弹性回复率和弹性模量的增大而增大，但随纳米压头尖端半径、断裂韧性和纳米硬度的增大而减小。当平均弹性回复率在17.5% ~ 20%范围内（最大弹性回复率在35% ~ 40%范围内），理论模型预测值与实验值吻合较好，平均弹性回复率小于5%。该模型可为分析脆性固体材料在磨粒去除过程中的表面生成特性提供理论指导。
Nanoindentation and nanoscratch tests of YAG single crystals were systematically performed. The mechanical properties including elastic recovery rate, elastic modulus, nano hardness and fracture toughness of YAG single crystals were obtained by the nanoindentation tests. The surface morphologies of the scratched grooves were analysed using scanning electron microscopy. The formation characteristics of YAG single crystals induced by varied-depth nanoscratch indicated that there was distinct brittle-to-ductile transition phenomenon during the scratching process. Surface radial cracks occurred prior to the edge-breaking phenomenon, and transverse cracks extending to the surface of the work material dominated the brittle removal of YAG single crystals. A theoretical model of the edge-breaking size during the nanoscratch process was developed by considering the stress intensity factor, elastic recovery rate, and residual force. This model indicated that the edge-breaking size increased as the normal force, average elastic recovery rate and elastic modulus increased, but decreased as the nanoindenter tip radius, fracture toughness and nano hardness increased. When the average elastic recovery rate was within 17.5%-20% (the maximum elastic recovery rate was within 35%-40%), the values predicted by the theoretical model agreed well with the experimental values, and the average en or was less than 5%. The model could provide theoretical guidance for analysing the surface generation characteristics of brittle solid materials during the abrasive processing at brittle removal regime.