Planar fault transformation and unfaulting of interstitial dislocation loops in irradiated L12-Ni3Al

Abstract

The present study has systematically investigated unfaulting mechanism of single-layer interstitial dislocation Loops (IDLs) in irradiated L12-Ni3Al to extend the existing unfaulting theory from pristine FCC lattice to the L12 ordered lattice, employing atomistic simulations combining continuum theory. Two types of variants for the IDLs have been determined with different planar faults enclosed in the Frank loop. The unfaulting routes of IDLs by Shockley partial loops have been unveiled through examining the energy barriers of superlattice planar fault transformation. The symmetry breaking occurring in the unfaulting processes were further elucidated and summarized. A continuum model has been formulated to enable quantitative theoretical analysis of the energetics of IDLs and prediction of the unfaulting threshold. These findings clarify the effects of complex faults and symmetry breaking on unfaulting behaviors of IDLs in irradiated L12-Ni3Al, and could be transferable to other L12 systems, and more generally, other ordered alloy systems.