Formation and growth of stacking fault tetrahedra in Ni via vacancy aggregation mechanism

Using molecular dynamics simulations, the formation and growth of stacking fault tetrahedra (SFT) are captured by vacancy cluster diffusion and aggregation mechanisms in Ni. The vacancy-tetrahedron acts as a nucleation point for SFT formation. Simulations show that perfect SFT can grow to the next size perfect SFT via a vacancy aggregation mechanism. The stopping and range of ions in matter (SRIM) calculations and transmission electron microscopy (TEM) observations reveal that SFT can form farther away from the initial cascade-event locations, indicating the operation of diffusion-based vacancy-aggregation mechanism.