Theoretical modelling of brittle-to-ductile transition load of KDP crystals on (001) plane during nanoindentation and nanoscratch tests
Theoretical modelling of brittle-to-ductile transition load of KDP crystals on (001) plane during nanoindentation and nanoscratch tests
复制标题
纳米压痕和纳米划痕测试过程中 KDP 晶体 (001) 平面脆性转变载荷的理论模型
DOI：
10.1016/j.jmrt.2020.09.131
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发表时间：
2020-11-01
影响因子：
6.4
通讯作者：
Zhang, Liangchi
中科院分区：
文献类型：
--
作者：
Li, Chen;Zhang, Yong;Zhang, Liangchi
KDP晶体具有宽的传输带宽、高的激光损伤阈值、大的非线性光学系数等优点，在惯性约束聚变和高功率激光器中得到了广泛的应用。但由于KDP晶体的高脆性和明显的各向异性，在加工过程中容易产生表面和亚表面损伤。这些损坏会降低KDP晶体元件的使用精度和寿命。研究KDP晶体的脆韧转变对实现晶体零件的高效精密加工具有重要意义。基于能量守恒定律和位错理论，建立了KDP晶体纳米压痕和纳米划痕过程中脆韧转变载荷的理论模型。该模型考虑了KDP晶体的各向异性。通过不同压头的纳米压痕和纳米划痕实验验证了脆韧转变载荷的理论模型。脆塑转变载荷的实验结果与理论结果吻合较好，表明该模型是可靠的。实验和理论结果表明，随着半锥角的增大，纳米压痕和纳米划痕过程中脆韧转变的临界载荷增大。在相同条件下，划痕的脆韧转变临界载荷低于压痕的临界载荷。结果还表明，KDP晶体在纳米压痕和纳米划痕过程中具有明显的各向异性。在划痕过程中，脆性断裂最有可能发生在沿着[100]取向。在相同的划痕条件下，[110]晶向比其它晶向更容易实现高表面质量的延性加工。(C)2020由Elsevier B.V.出版
KDP single crystals are widely used in inertial confinement fusion and high power lasers due to the wide transmission band, high laser damage threshold, large nonlinear optical coefficient, etc. However, surface and subsurface damages are easily induced into the KDP crystal components during the machining process due to its high brittleness and distinct anisotropy. These damages will reduce the service accuracy and life of KDP crystal components. It is of great significance to study the brittle-to-ductile transition of KDP crystals to achieve high efficiency and precision machining of crystal components. In this work, a theoretical model of brittle-to-ductile transition load during the nanoindentation and nanoscratch processes of KDP crystals was established based on the energy conservation law and dislocation theory. This model took the anisotropy of KDP crystals into account. Nanoindentation and nanoscratch experiments by using different indenters were performed to verify the theoretical model of brittle-to-ductile transition load. The experimental results of the brittle-to-ductile transition load agreed well with the theoretical results, which indicated that the model was reliable. Both experimental and theoretical results showed that the critical load of brittle-to-ductile transition during the nanoindentation and nanoscratch processes increased as the half cone angle increased. In addition, the critical load of brittle-to-ductile transition load of the scratch was lower than that of the indentation under the same condition. The results also demonstrated that KDP crystals had distinct anisotropy during the nanoindentation and nanoscratch process. Brittle fracture was most likely to occur along [100] orientation during the scratch process. Under the same scratching condition, [110] orientation was prone to achieving ductile machining with high surface quality compared with other orientations. (C) 2020 Published by Elsevier B.V.