First–Principles Study on Twin Generation Induced by Symmetry Breaking in Cu–In Alloy

Abstract

We investigated deformation twinning in Cu–In alloy with even distribution of In atoms through density functional theory (DFT) calculations. Twinnability of Cu–In alloy were evaluated based on the general stacking fault energies (GSFE) and compared with those of pure Cu, Cu–Al, and Cu–Zn alloys. Cu–In alloy demonstrated a substantial reduction in stacking fault energies. Especially, the twinnability is significantly enhanced along a specific path among six available partial slip directions, owing to the symmetry–breaking effect induced by In atoms. The local lattice strain by In atoms in Cu matrix led to more pronounced symmetry breaking compared to Al and Zn, thereby facilitating twin formation in specific directions. Since the local lattice strain is randomly distributed in the grain, the energy barrier to generate a twin can be lowered in all directions, accelerating twin formation throughout the grain.