Anomalous interactions of non-coplanar dislocation dipole in intermetallic compounds

Abstract

Intermetallic precipitates are strategically introduced to strengthen metallic alloys. Severe plastic deformation associated with dislocations interactions often causes destabilization of intermetallic precipitates in metallic alloys. Based on molecular dynamics simulations of non-coplanar dislocation dipole interactions, we reported anomalous reactions of forming vacancy-type defects (vacancy cluster, void and prismatic dislocation loop) in typical intermetallic compounds (i.e. L1₂-Ni₃Al, L1₀-TiAl, and B2-NiAl). Compared with the reactions in metals, the formation of vacancy-type defects is attributed to the larger core energies and interaction forces of a dislocation dipole and the lowering formation energies of vacancies within the dislocation cores in intermetallic compounds. These vacancy-type defects are immobile and pin the motion of dislocations, locally disorder the crystal, and facilitate self-diffusion of alloying elements, consequently deteriorating structural stability of intermetallic precipitates.