Key Laboratory for Precision and Non-Traditional Machining Technology of Ministry of Education, Dalian University of Technology, Dalian 116024, China.
Key laboratory of Marine Materials and Related Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China.
Sci Rep. 2017 Mar 28;7:45405. doi: 10.1038/srep45405.
The formation mechanism considers fivefold deformation twins originating from the grain boundaries in a nanocrystalline material, resulting in that fivefold deformation twins derived from a single crystal have not been reported by molecular dynamics simulations. In this study, fivefold deformation twins are observed in a single crystal of face-centered cubic (fcc) alloy. A new formation mechanism is proposed for fivefold deformation twins in a single crystal. A partial dislocation is emitted from the incoherent twin boundaries (ITBs) with high energy, generating a stacking fault along {111} plane, and resulting in the nucleating and growing of a twin by the successive emission of partials. A node is fixed at the intersecting center of the four different slip {111} planes. With increasing stress under the indentation, ITBs come into being close to the node, leading to the emission of a partial from the node. This generates a stacking fault along a {111} plane, nucleating and growing a twin by the continuous emission of the partials. This process repeats until the formation of fivefold deformation twins.
该形成机制考虑了源自纳米晶材料晶界的五重变形孪晶，导致分子动力学模拟尚未报道源自单晶的五重变形孪晶。在这项研究中，在面心立方 (fcc) 合金的单晶中观察到五重变形孪晶。提出了单晶中五重变形孪晶的新形成机制。部分位错从具有高能量的非相干孪晶界 (ITB) 发射，沿 {111} 面产生层错，通过部分位错的连续发射导致孪晶的成核和生长。节点固定在四个不同的滑移 {111} 面的相交中心。随着压痕下的应力增加，ITB 接近节点，导致从节点发射部分位错。这会沿着 {111} 面产生层错，通过连续发射部分位错来成核和生长孪晶。这个过程一直重复，直到形成五重变形孪晶。
