Stacking Fault Energy, Dislocation Density, and Twin Fault Probability Determined by Neutron Diffraction Peak Profile Analysis in CrCoNi Based Medium Entropy Alloys

Abstract

Neutron diffraction peak profile analysis was used to determine stacking fault energy (SFE), dislocation density, and twin fault probability (P_tw) in CrCoNi and CrCoNiFe medium entropy alloys at 293K and 140K. The CrCoNi shows higher P_tw (up to 3.8%) and dislocation density (up to 9.7 x 10¹⁵ m^-2) than CrCoNiFe (1.3% and 3.4 x 10¹⁵ m^-2, respectively) at 293K. Meanwhile, at 140K, the P_tw in CrCoNiFe increases significantly to 4.4%. The dominant twinning deformation is due to the lower SFEs of CrCoNi (16.1 mJ/m²) at 293K and CrCoNiFe (7.4 mJ/m²) at 140K compared to 32.1 mJ/m² for CrCoNiFe at 293K.