Ultrahard BCC-AlCoCrFeNi bulk nanocrystalline high-entropy alloy formed by nanoscale diffusion-induced phase transition  

作　　者：Junjie Wang Zongde Kou Shu Fu Shangshu Wu Sinan Liu Mengyang Yan Zhiqiang Ren Di Wang Zesheng You Si Lan Horst Hahn Xun-Li Wang Tao Feng 

机构地区：[1]Herbert Gleiter Institute of Nanoscience,School of Material Science and Engineering,Nanjing University of Science and Technology,Nanjing 210094,China [2]Institute of Nanotechnology,Karlsruhe Institute of Technology,Karlsruhe 76021,Germany [3]Department of Physics,City University of Hong Kong,Hong Kong,China [4]Center for Neutron Scattering,Shenzhen Research Institute,City University of Hong Kong,Shenzhen 518057,China

出　　处：《Journal of Materials Science & Technology》2022年第20期29-39,共11页材料科学技术（英文版）

基　　金：the Equipment Advance Research field Fund(Nos.80922010401);the National Key R&D Program of China(Nos.2021YFB3802800);the Guangdong-Hong Kong-Macao Joint Laboratory for Neutron Scat-tering Science and Technology,the Fundamental Research Funds for the Central Universities(Nos.30919011404 and 30919011107);the National Natural Science Foundation of China(Nos.51871120 and 51571119);the Natural Science Foundation of Jiangsu Province(No.BK20200019);the support from the Qing Lan project and the distinguished professor project of Jiangsu province;the support by Shenzhen Science and Technology Innovation Committee(No.JCYJ20170413140446951);the Research Grants Council of Hong Kong(No.City U 11215917)。

摘　　要：In the current work,the BCC-AlCoCrFeNi bulk nanocrystalline high-entropy alloy(nc-HEA)with ultrahigh hardness was formed by nanoscale diffusion-induced phase transition in a nanocomposite.First,a dual-phase Al/CoCrFeNi nanocrystalline high-entropy alloy composite(nc-HEAC)was prepared by a laser source inert gas condensation equipment(laser-IGC).The as-prepared nc-HEAC is composed of well-mixed FCC-Al and FCC-CoCrFeNi nanocrystals.Then,the heat treatment was used to trigger the interdiffusion between Al and CoCrFeNi nanocrystals and form an FCC-AlCoCrFeNi phase.With the increase of the annealing temperature,element diffusion intensifies,and the Al Co Cr Fe Ni phase undergoes a phase transition from FCC to BCC structure.Finally,the BCC-AlCoCrFe Ni bulk nc-HEA with high Al content(up to 50 at.%)was obtained for the first time.Excitingly,the nc-HEAC(Al-40%)sample exhibits an unprecedented ultra-high hardness of 1124 HV after annealing at 500℃ for 1 h.We present a systematic investigation of the relationship between the microstructure evolution and mechanical properties during annealing,and the corresponding micro-mechanisms in different annealing stages are revealed.The enhanced nanoscale thermal diffusion-induced phase transition process dominates the mechanical performance evolution of the nc-HEACs,which opens a new pathway for the design of high-performance nanocrystalline alloy materials.

关 键 词：High-entropy alloy NANOCRYSTALLINE Composites Diffusion-induced phase transition Mechanical Inert gas condensation 

分 类 号：TG139[一般工业技术—材料科学与工程]