Department of Control Engineering, Faculty of Electrical Engineering , Czech Technical University in Prague , Technicka 2 , 16627 Prague 6 , Czech Republic.
Engineering Materials, Faculty of Engineering and Physical Sciences , University of Southampton , Southampton SO17 1BJ , U.K.
ACS Appl Mater Interfaces. 2019 Dec 11;11(49):46296-46302. doi: 10.1021/acsami.9b12235. Epub 2019 Nov 27.
Achieving the theoretical strength of a metallic alloy material is a demanding task that usually requires utilizing one or more of the well-established routes: (1) Decreasing the grain size to stop or slow down the dislocation mobility, (2) adding external barriers to dislocation pathways, (3) altering the crystal structure, or (4) combining two of the previous discrete strategies, that is, implementing crystal seeds into an amorphous matrix. Each of the outlined methods has clear limitations; hence, further improvements are required. We present a unique approach that envelops all the different strength-building strategies together with a new phenomenon-phase transition. We simulated the plastic deformation of a Zr-Nb nanolayered alloy using molecular dynamics and ab initio methods and observed the transition of Zr from hexagonal close-packed to face-centered cubic and then to body-cenetered cubic during compression. The alloy, which was prepared by magnetron sputtering, exhibited near-theoretical hardness (10.8 GPa) and the predicted transition of the Zr structure was confirmed. Therefore, we have identified a new route for improving the hardness of metallic alloys.
实现金属合金材料的理论强度是一项艰巨的任务，通常需要利用一种或多种成熟的途径：（1）减小晶粒尺寸以阻止或减缓位错的迁移，（2）在外加位错路径上添加障碍物，（3）改变晶体结构，或（4）结合前两种离散策略，即向非晶基体中引入晶种。所概述的方法都有明显的局限性；因此，需要进一步改进。我们提出了一种独特的方法，将所有不同的增强强度策略与一种新的相变现象结合在一起。我们使用分子动力学和第一性原理方法模拟了 Zr-Nb 纳米层状合金的塑性变形，并观察到 Zr 在压缩过程中从六方密堆积转变为面心立方，然后转变为体心立方。通过磁控溅射制备的合金表现出接近理论硬度（10.8 GPa），并证实了 Zr 结构的预测转变。因此，我们已经确定了一种提高金属合金硬度的新途径。
