Nonlinear fracture of two-dimensional transition metal carbides (MXenes)
Nonlinear fracture of two-dimensional transition metal carbides (MXenes)
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DOI：
10.1016/j.engfracmech.2020.106978
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发表时间：
2020-05
影响因子：
5.4
通讯作者：
Congjie Wei;Chenglin Wu
中科院分区：
文献类型：
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作者：
Congjie Wei;Chenglin Wu
MXene作为一种新发现的二维材料，具有特殊的热电子性质。然而，它的力学行为，特别是断裂，仍然是未知的。原位SEM拉伸实验表明，MXene的断裂是非线性的，与其他二维材料相比，其软化阶段较长，这可能是由MXene的各向异性和相对较厚的单层膜引起的。本文采用分子动力学（MD）模拟方法研究了两种不同单层厚度的MXene（Ti_2C和Ti_3C_2）的各向异性断裂行为。研究了原始的和有缺陷的MXene。结果表明：（1）MXene倾向于沿沿着Z字形方向断裂，（2）裂纹尖端的原子空位对整体断裂行为的影响有限，（3）由于“减薄”过程，较厚的单层可以产生较大的内聚区，（4）对于混合模式断裂，预期复杂的断裂路径。
As a newly discovered two-dimensional (2D) material group, MXene has exceptional thermal- electronic properties. However, its mechanical behavior, especially fracture, remains unexplored. In-situ SEM tensile experiments show that the fracture of MXene is quite nonlinear with a much-prolonged softening stage in comparison with other 2D materials, which is suspected to be caused by the anisotropy and relatively thick monolayer of MXenes. In this work, molecular dynamic (MD) modeling is conducted to investigate the anisotropic fracture behavior of two types of MXenes (Ti2C and Ti3C2) with different monolayer thickness. Both pristine and defected MXenes are investigated. Results show that: (1) MXene tends to fracture along zigzag direction, (2) atomic vacancies at the crack tip have limited effects on the overall fracture behavior, (3) a thicker monolayer can produce a larger cohesive zone due to the ‘thinning’ process, (4) complex fracture paths are to be expected for mixed-mode fractures.