Achieving superb strength in single-phase FCC alloys via maximizing volume misfit

作者：Li, Zhongtao; Ma, Shihua; Zhao, Shijun^*; Zhang, Weidong; Peng, Fei; Li, Qian; Yang, Tao; Wu, Chia-Yi; Wei, Daixiu; Chou, Yi-Chia; Liaw, Peter K.; Gao, Yanfei; Wu, Zhenggang

来源：Materials Today, 2023, 63: 108-119.

DOI：10.1016/j.mattod.2023.02.012

• Single-phase face-centered cubic alloys
• Volume misfit
• Solid-solution strengthening
• Grain-boundary strengthening
• Mechanical properties

Single-phase face-centered cubic (SP-FCC) alloys normally possess low strength. Conventionally strengthening strategies inevitably cause significant ductility sacrifice. Here, a single-phase Ni-based FCC alloy with a superb yield strength of-1.05GPa and a good ductility of 37% is designed through maximizing the volume misfits. The misfit of the purposely targeted Ni80Mo20 alloy is severer than all existing FCC alloys, bringing the alloy a highest-ever Hall-Petch coefficient (kHP = 1034 MPa center dot lm1/2) and a pronounced solid solution strengthening (Drss = 224 MPa). Current work yields two surprising and novel findings for SP-FCC alloys. First, volume misfit is a good pertinent indicator of kHP. Second, the conventional impression about the sole contribution of edge dislocations to strengthening in SP-FCC alloys may no longer hold; instead, screw dislocations can also kick in once the nonsphericity of the solute-induced stress field reaches a critical value. Altogether, this work paves a new avenue of pursuing ultimate strengthening without significant ductility sacrifice for SP-FCC alloys relying on the volume -misfit-maximization strategy.

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