Yang Tianhai, Cai Bin, Shi Yunjia, Wang Mingxing, Zhang Guopeng
School of Physics, Key Lab of Materials Physics, Zhengzhou University, No.75 Daxue Road, Zhengzhou, 450052, China.
School of Physics, Key Lab of Materials Physics, Zhengzhou University, No.75 Daxue Road, Zhengzhou, 450052, China.
Micron. 2021 Aug;147:103082. doi: 10.1016/j.micron.2021.103082. Epub 2021 May 15.
Pre-alloyed CoCrFeMnNi high-entropy alloy (HEA) powders were prepared by gas atomization and consequently hot pressing sintered (HPS) at 1100 °C for 2 h for fabrication bulk materials. Sintered equiatomic CoCrFeMnNi HEA exhibited a homogeneous FCC structured single-phase solid solution and equiaxed grains with an average size of ∼16 μm. Analyses using TEM showed that sheet-like metastable structures with a size of ∼55 to 160 nm were formed in the sintered bulks. The nano-sized metastable structures were inherited from the gas atomized CoCrFeMnNi powders with nano-sized crystallites formed during the rapid solidification process. The room temperature yield and ultimate tensile strength of sintered HEA reached 358 and 778 MPa, respectively, and the alloy kept excellent plasticity of ∼28 %. Investigations of the deformation substructures at specific strain levels with EBSD revealed the sintered CoCrFeMnNi HEA kept FCC structured single phase and the main deformation mechanism was dislocation slip. The strengthening mechanism can be attributed to the combination effects of grain refinement and the presence of nano-sized metastable structures.
通过气体雾化制备预合金化的CoCrFeMnNi高熵合金（HEA）粉末，随后在1100℃下进行热压烧结（HPS）2小时以制备块状材料。烧结的等原子CoCrFeMnNi HEA呈现出均匀的面心立方（FCC）结构单相固溶体和平均尺寸约为16μm的等轴晶粒。使用透射电子显微镜（TEM）分析表明，在烧结块体中形成了尺寸约为55至160nm的片状亚稳结构。这些纳米尺寸的亚稳结构继承自气体雾化的CoCrFeMnNi粉末，在快速凝固过程中形成了纳米尺寸的微晶。烧结HEA的室温屈服强度和极限抗拉强度分别达到358MPa和778MPa，并且该合金保持了约28%的优异塑性。利用电子背散射衍射（EBSD）对特定应变水平下的变形亚结构进行研究表明，烧结的CoCrFeMnNi HEA保持FCC结构单相，主要变形机制是位错滑移。强化机制可归因于晶粒细化和纳米尺寸亚稳结构的共同作用。
