Effects of tungsten additions on the microstructure and mechanical properties of CoCrNi medium entropy alloys

By Ruo-bin Chang, W. Fang, X. Bai, C. Xia, Xin Zhang, Hao Yu, Bao-xi Liu, F. Yin. Journal of Alloys and Compounds, 2019

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Abstract W element has a much higher atomic radius and Young's modulus than that of Co, Cr and Ni elements. In this work, the effects of W additions on recrystallized behaviors, mechanical properties and plastic deformation of CoCrNi medium entropy alloy are investigated. The results indicate recrystallized behaviors of alloys are retarded as the increase of W content. The activation energy of (CoCrNi)97W3 alloy dramatically increases (393.3 kJ/mol), indicating slow grain coarsening kinetics. For completely recrystallized alloys annealed at 900 °C with low W content (1 at. %), grain boundary hardening is the predominant reason for the yield strength increment compared with the CoCrNi alloy, but for alloys with high W content (3 at. %), the solid solution hardening and grain boundary hardening have the same contributions on the yield strength increment (∼120 MPa). The lattice friction stress and Hall-Petch slope of (CoCrNi)97W3 alloy are 291 MPa and 487 MPa μm−0.5, respectively. Overall, 3 at. % W additions improve yield strength of CoCrNi alloy by ∼33%, and maintain high ductility and work hardening ability.

Subfields: Aerospace Engineering, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/e3c8cf3e9bb24638011cddb8e557fdfa9e114d56