Simultaneous enhancement of strength and ductility via microband formation and nanotwinning in an L1_(2)-strengthened alloy  

作　　者：Lu Yang Dingshan Liang Zhuo Cheng Ranxi Duan Chuanxin Zhong Junhua Luan Zengbao Jiao Fuzeng Ren 

机构地区：[1]Department of Materials Science and Engineering,Southern University of Science and Technology,Shenzhen 518055,China [2]Department of Materials Science and Engineering,City University of Hong Kong,Hong Kong 999077,China [3]Department of Mechanical Engineering,The Hong Kong Polytechnic University,Hong Kong 999077,China

出　　处：《Fundamental Research》2024年第1期147-157,共11页自然科学基础研究（英文版）

基　　金：The authors also thank the Microscope and Imaging Center at Southern University of Science and Technology,China.This work was financially supported by the National Natural Science Foundation of China(52122102);Guangdong Innovative&Entrepreneurial Research Team Program(2016ZT06C279);APT research was conducted at the Inter-University 3D APT Unit of City University of Hong Kong(CityU),which is supported by the CityU grant(9360161).

摘　　要：Metallic alloys with high strength and large ductility are required for extreme structural applications.However,the achievement of ultrahigh strength often results in a substantially decreased ductility.Here,we report a strategy to achieve the strength-ductility synergy by tailoring the alloy composition to control the local stacking fault energy(SFE)of the face-centered-cubic(fcc)matrix in an L1_(2)-strengthened superlattice alloy.As a proof of concept,based on the thermodynamic calculations,we developed a non-equiatomic CoCrNi_(2)(Al_(0.2)Nb_(0.2))alloy using phase separation to create a near-equiatomic low SFE disordered CoCrNi medium-entropy alloy matrix with in situ formed high-content coherent Ni_(3)(Al,Nb)-type ordered nanoprecipitates(∼12 nm).The alloy achieves a high tensile strength up to 1.6 GPa and a uniform ductility of 33%.The low SFE of the fcc matrix promotes the formation of nanotwins and parallel microbands during plastic deformation which could remarkably enhance the strain hardening capacity.This work provides a strategy for developing ultrahigh-strength alloys with large uniform ductility.

关 键 词：L1_(2)-strengthened superlattice alloy Stacking fault energy NANOTWINS MICROBANDS Strain hardening 

分 类 号：TG13[一般工业技术—材料科学与工程]