Luo Hubin, Sheng Hongwei, Zhang Hongliang, Wang Fengqing, Fan Jinkui, Du Juan, Ping Liu J, Szlufarska Izabela
Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China.
Department of Materials Science and Engineering, University of Wisconsin, Madison, WI, 53706-1595, USA.
Nat Commun. 2019 Aug 9;10(1):3587. doi: 10.1038/s41467-019-11505-1.
Dislocation activity is critical to ductility and the mechanical strength of metals. Dislocations are the primary drivers of plastic deformation, and their interactions with each other and with other microstructural features such as grain boundaries (GBs) lead to strengthening of metals. In general, suppressing dislocation activity leads to brittleness of polycrystalline materials. Here, we find an intermetallic that can accommodate large plastic strain without the help of dislocations. For small grain sizes, the primary deformation mechanism is GB sliding, whereas for larger grain sizes the material deforms by direct amorphization along shear planes. The unusual deformation mechanisms lead to the absence of traditional Hall-Petch (HP) relation commonly observed in metals and to an extended regime of strength weakening with grain refinement, referred to as the inverse HP relation. The results are first predicted in simulations and then confirmed experimentally.
位错活动对于金属的延展性和机械强度至关重要。位错是塑性变形的主要驱动力，它们彼此之间以及与诸如晶界（GBs）等其他微观结构特征的相互作用会导致金属强化。一般来说，抑制位错活动会导致多晶材料变脆。在此，我们发现一种金属间化合物，它能够在没有位错帮助的情况下承受大的塑性应变。对于小晶粒尺寸，主要变形机制是晶界滑动，而对于较大晶粒尺寸，材料通过沿剪切面直接非晶化而变形。这些不寻常的变形机制导致在金属中通常观察到的传统霍尔 - 佩奇（HP）关系不存在，并且随着晶粒细化出现强度减弱的扩展区域，称为反HP关系。结果首先在模拟中得到预测，然后通过实验得到证实。
