Two-fold effect of compressive stress on stacking-fault tetrahedron formation in face-centered cubic metals

Molecular dynamics simulations were employed to investigate the compressive stress effect on SFTs in Cu and Ni. The results show that compressive stress exerts a dual effect on SFT formation: on one hand, it facilitates the formation of small-size SFTs in Ni; on the other hand, the compressive stress can also disrupt the stableness of pre-existing SFTs. Furthermore, the dual effect of compressive stress on SFTs is verified in terms of energy. It is revealed that compressive stress can reduce the transformation barrier from vacancy platelets to SFTs, thereby promoting the formation of SFTs. Additionally, the transformation from SFT to Frank dislocation loop induced by compressive stress is further investigated in terms of enthalpy. Finally, the structural evolution of SFTs in Cu and Ni are summarized in the compressive stress SFT size space. The present work provided a deep understanding of the behavior of SFT in stress field.