Amorphization-governed elasto-plastic deformation under nanoindentation in cubic (3C) silicon carbide
Amorphization-governed elasto-plastic deformation under nanoindentation in cubic (3C) silicon carbide
复制标题
纳米压痕下立方（3C）碳化硅非晶化控制的弹塑性变形
DOI：
10.1016/j.ceramint.2020.02.009
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发表时间：
2020-06-01
影响因子：
5.2
通讯作者：
Hartmaier, Alexander
中科院分区：
文献类型：
--
作者：
Zhao, Liang;Alam, Masud;Hartmaier, Alexander
非晶化在机械载荷下的陶瓷变形中起着重要作用。本文采用分子动力学模拟方法研究了单晶立方碳化硅（3C-SiC）在球形纳米压痕中的弹塑性变形机制。重点讨论了压痕诱导的非晶化及其与其它变形方式的相互作用。首先，合适的经验势能够准确地表征单晶3C-SiC的机械和缺陷特性，以及从3C-SiC到非晶SiC的相变倾向，是合理地选择通过基准测试不同的经验势与实验数据和密度泛函理论计算。随后，在纳米压痕单晶3C-SiC的非均匀的弹塑性转变，以及它们对晶体取向的依赖性，进行了研究。采用基于径向分布函数和键角分布的组合方法分析了包括非晶化在内的相变。我们的模拟结果表明，在塑性引发相关的“pop-in”事件之前，每个缩进的单晶3C-SiC经历由非晶结构的形成控制的纯准弹性变形。并且对于小的压痕深度，这种非晶化过程是完全可逆的。进一步的非晶化和位错形核共同主导了3C-SiC纳米压痕的初始塑性。结果表明，在3C-SiC（010）中，压痕诱导的缺陷区主要由非晶相和位错组成，而在（110）和（111）两个取向中，压痕诱导的缺陷区主要由位错和非晶相组成。
Amorphization plays an important role in ceramic deformation under mechanical loading. In the present work, we investigate the elasto-plastic deformation mechanisms of monocrystalline cubic silicon carbide (3C-SiC) in spherical nanoindentation by means of molecular dynamics simulations. The indentation-induced amorphization and its interactions with other deformation modes are emphasized. Initially, the suitable empirical potential capable of accurately characterizing the mechanical and defect properties of monocrystalline 3C-SiC, as well as the propensity of phase transformation from 3C-SiC to amorphous SiC, is rationally selected by benchmarking of different empirical potentials with experimental data and density functional theory calculations. Subsequently, the inhomogeneous elastic-plastic transitions during nanoindentation of monocrystalline 3C-SiC, as well as their dependence on crystallographic orientation, are investigated. Phase transformations including amorphization are analyzed using combined methods based on radial distribution function and bond angle distribution. Our simulation results demonstrate that before plasticity initiation-related "pop-in" event, each indented-mono-crystalline 3C-SiC experiences a pure quasi-elastic deformation governed by the formation of amorphous structures. And this process of amorphization is fully reversible for small indentation depths. Further amorphization and dislocation nucleation jointly dominate the incipient plasticity in 3C-SiC nanoindentation. It is found that the indentation-induced defect zone composed of amorphous phase and dislocations is more pronounced in 3C-SiC(010) than that in the other two orientations of (110) and (111).