Atomistic origin of brittle-to-ductile transition behavior of polycrystalline 3C-SiC in diamond cutting
Atomistic origin of brittle-to-ductile transition behavior of polycrystalline 3C-SiC in diamond cutting
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DOI：
10.1016/j.ceramint.2021.05.098
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发表时间：
2021-07-20
影响因子：
5.2
通讯作者：
Sun, Tao
中科院分区：
文献类型：
--
作者：
Zhao, Liang;Hu, Wangjie;Sun, Tao
硬脆多晶陶瓷的可加工性与其内部微观结构及其适应变形行为密切相关。本文采用分子动力学模拟方法研究了多晶3C-SiC在金刚石切削过程中的脆韧转变机制。模拟结果揭示了位错滑移和非晶化主导的韧性变形和沿沿着晶界介导的脆性断裂共存，以及各变形模式与加工力变化和加工表面形貌的相关性。此外，沿晶断裂、晶界滑移和晶粒上拉也是多晶3C-SiC的脆性变形模式。上述非均质变形模式之间的强烈竞争决定了多晶3C-SiC切槽过程中的脆韧转变行为。模拟结果还表明，晶粒尺寸对金刚石切削下多晶3C-SiC的脆韧转变和材料变形行为有很大的影响。
The machinability of hard brittle polycrystalline ceramic has a strong correlation with internal microstructures and their accommodated deformation behavior. In the present work, we investigate the mechanisms governing the brittle-to-ductile transition behavior of polycrystalline 3C-SiC in diamond cutting by means of molecular dynamics simulations. Simulation results reveal the co-existence of dislocation slip and amorphizationdominated ductile deformation and cracking along grain boundaries-mediated brittle fracture, as well as the correlation of individual deformation modes with machining force variation and machined surface morphology. In addition, inter-granular fracture, grain boundary sliding and grain pull-up are also operating brittle deformation modes of polycrystalline 3C-SiC. The strong competition between above heterogeneous deformation modes determines the brittle-to-ductile transition behavior in grooving of polycrystalline 3C-SiC. Simulation results also demonstrate that grain size has a strong impact on the brittle-to-ductile transition and material deformation behavior of polycrystalline 3C-SiC under diamond cutting.