Chen Sijing, Oh Hyun Seok, Gludovatz Bernd, Kim Sang Jun, Park Eun Soo, Zhang Ze, Ritchie Robert O, Yu Qian
Department of Materials Science & Engineering, Center of Electron Microscopy and State Key Laboratory of Silicon Materials, Zhejiang University, 310027, Hangzhou, China.
Research Institute of Advanced Materials, Department of Materials Science and Engineering, Seoul National University, Seoul, 08826, Republic of Korea.
Nat Commun. 2020 Feb 11;11(1):826. doi: 10.1038/s41467-020-14641-1.
Strategies involving metastable phases have been the basis of the design of numerous alloys, yet research on metastable high-entropy alloys is still in its infancy. In dual-phase high-entropy alloys, the combination of local chemical environments and loading-induced crystal structure changes suggests a relationship between deformation mechanisms and chemical atomic distribution, which we examine in here in a Cantor-like CrMnFeCoNi alloy, comprising both face-centered cubic (fcc) and hexagonal closed packed (hcp) phases. We observe that partial dislocation activities result in stable three-dimensional stacking-fault networks. Additionally, the fraction of the stronger hcp phase progressively increases during plastic deformation by forming at the stacking-fault network boundaries in the fcc phase, serving as the major source of strain hardening. In this context, variations in local chemical composition promote a high density of Lomer-Cottrell locks, which facilitate the construction of the stacking-fault networks to provide nucleation sites for the hcp phase transformation.
涉及亚稳相的策略一直是众多合金设计的基础，但亚稳高熵合金的研究仍处于起步阶段。在双相高熵合金中，局部化学环境与加载诱导的晶体结构变化的结合表明了变形机制与化学原子分布之间的关系，我们在此对一种类坎托型CrMnFeCoNi合金进行研究，该合金包含面心立方（fcc）相和六方密排（hcp）相。我们观察到部分位错活动会导致稳定的三维堆垛层错网络。此外，在塑性变形过程中，较强的hcp相的比例通过在fcc相的堆垛层错网络边界处形成而逐渐增加，成为应变硬化的主要来源。在这种情况下，局部化学成分的变化促进了高密度的洛默 - 科特雷尔位错塞积群的形成，这有助于堆垛层错网络的构建，为hcp相转变提供形核位置。
