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

• Published in: Materials today (Kidlington, England) Vol. 63; pp. 108 - 119
• Main Authors: 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
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.03.2023
• Subjects: Grain-boundary strengthening; Mechanical properties; Single-phase face-centered cubic alloys; Solid-solution strengthening; Volume misfit; Mechanical properties; Grain-boundary strengthening; Solid-solution strengthening; Volume misfit; Single-phase face-centered cubic alloys
• ISSN: 1369-7021; 1873-4103
• DOI: 10.1016/j.mattod.2023.02.012

[Display omitted] •Single-phase binary FCC alloy with superb strength is designed through volume-misfit-maximization-strategy.•The targeted Ni80Mo20 exhibits a yield strength of ∼1.05 GPa while maintaining ∼40% elongation.•Unprecedented volume misfit brings a highest-ever Hall-Petch coefficient (1034 MPa·μm1/2) and a pronounced solid solution strengthening (224 MPa).•Volume misfit is a good pertinent indicator of kHP.•Screw dislocations can control the strengthening in SP-FCC alloys. 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·μm1/2) and a pronounced solid solution strengthening (Δσss = 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.