Chen Shuai, Liu Ping, Pei Qingxiang, Yu Zhi Gen, Aitken Zachary H, Li Wanghui, Wu Zhaoxuan, Banerjee Rajarshi, Srolovitz David J, Liaw Peter K, Zhang Yong-Wei
Materials Genome Institute, Shanghai University, Shanghai 200444, China.
Institute of High Performance Computing (IHPC), Agency for Science, Technology and Research (A*STAR), 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632, Republic of Singapore.
Sci Adv. 2023 Oct 13;9(41):eadi5817. doi: 10.1126/sciadv.adi5817.
Understanding the relationship among elemental compositions, nanolamellar microstructures, and mechanical properties enables the rational design of high-entropy alloys (HEAs). Here, we construct nanolamellar AlCoCuFeNi HEAs with alternating high- and low-Al concentration layers and explore their mechanical properties using a combination of molecular dynamic simulation and density functional theory calculation. Our results show that the HEAs with nanolamellar structures exhibit ideal plastic behavior during uniaxial tensile loading, a feature not observed in homogeneous HEAs. This remarkable ideal plasticity is attributed to the unique deformation mechanisms of phase transformation coupled with dislocation nucleation and propagation in the high-Al concentration layers and the confinement and slip-blocking effect of the low-Al concentration layers. Unexpectedly, this ideal plasticity is fully reversible upon unloading, leading to a remarkable shape memory effect. Our work highlights the importance of nanolamellar structures in controlling the mechanical and functional properties of HEAs and presents a fascinating route for the design of HEAs for both functional and structural applications.
了解元素组成、纳米层状微观结构和力学性能之间的关系有助于合理设计高熵合金（HEA）。在此，我们构建了具有交替高铝浓度层和低铝浓度层的纳米层状AlCoCuFeNi高熵合金，并结合分子动力学模拟和密度泛函理论计算来探究其力学性能。我们的结果表明，具有纳米层状结构的高熵合金在单轴拉伸加载过程中表现出理想的塑性行为，这一特性在均匀高熵合金中并未观察到。这种显著的理想塑性归因于在高铝浓度层中发生的相变与位错形核和传播相结合的独特变形机制，以及低铝浓度层的限制和滑移阻碍效应。出乎意料的是，这种理想塑性在卸载时完全可逆，从而导致显著的形状记忆效应。我们的工作突出了纳米层状结构在控制高熵合金的力学和功能性能方面的重要性，并为设计用于功能和结构应用的高熵合金提供了一条引人入胜的途径。
