Speakers

Stacking fault energy (SFE)  is a critical parameter in controlling the deformation mechanisms of metallic materials and alloys. Low-SFE alloys exhibit deformation twinning (DT) and/or the formation of HCP martensite, which enhance the strain-hardening rate (SHR) and lead to good strength-elongation balance.  The present study reports the effet of SFE and grain size on the room temperature tensile-behavior of for FCC High-Entropy Alloys with the compositions of Co₄₀₋ₓCr₂₀Fe₂₀Mn₂₀Niₓ (x = 10, 15, 30) .  Samples with the various grain sizes ranging from 2 µm to 140 µm were obtained by HPT-deformation and  heat treatment.  The Ni10 and Ni15 specimens exhibited higher tensile strength and larger elongation-to-failure compared to the Ni30. The low SFE Ni10 and Ni15 showed the higher density of DTs and HCP phase compared to the high SFE Ni30 HEA. It was also revealed that volume fraction of the HCP phase increases with the grain size upto a critical size then decreases.  The critical grain size also depends on Ni content and was 26 μm for Ni10 and 18 μm for Ni15, respectively.

Effect of SFE on low cycle fatigue of Co-Cr-Mo-Ni MEAs will be also explained