[T19] High Entropy Alloys

[14D-T19-05] Unique High Temperature Deformation Behavior of a Harmonically Structured High Entropy CrMnFeCoNi Alloy

*S. Onoue¹, T. Ito², S. Hosogi¹, M. Kawabata³, H. Fujiwara¹, K. Ameyama¹ (1.Ritsumeikan University, Japan, 2.Osaka University, Japan, 3.Ritsumeikan Global Innovation Research Organization, Japan)

Keywords:compression test, activation energy, grain refinement, pseudo-superplasticity, strain rate sensitivity

The Harmonic Structure (HS) design was applied to the high entropy CrMnFeCoNi alloy, and the high-temperature deformation behavior of the alloy was studied by compression tests at various strain rates at 1073 K and 1173 K. The stress-strain curves of homogeneous and HS compacts were remarkably different and quite unique. That is, the HS specimen showed remarkable stress reduction during deformation. From the point of view of the activation energy for the high temperature compression test, the HS compact showed the activation energy decrease with the true strain, while the homogeneous structure compacts were almost independent with the true strain. Thus, it can be said that the grain refinement during deformation in the HS compact greatly affected the activation energy for deformation. In addition, the HS compacts had a strain rate sensitivity value of more than 0.5 at 1173 K, indicating that the HS compacts exhibited pseudo-superplastic deformation.