Molecular dynamics simulations of interaction between a super edge dislocation and interstitial dislocation loops in irradiated L12-Ni3Al

Abstract

The study employed MD simulations to investigate the interactions between a $〈1\overline{1}0〉$ super-edge dislocation, consisting of the four Shockley partials, and interstitial dislocation loops (IDLs) in irradiated $L{1}_2$-Ni₃Al. Accounting for symmetry breakage in the $L{1}_2$ lattice, the superlattice planar faults with four distinct fault vectors have been considered for different IDL configurations. The detailed dislocation reactions and structural evolution events were identified as the four partials interacted with various IDL configurations. The slipping characteristics of Shockley partials within the IDLs and the resultant shearing and looping mechanisms were also clarified, revealing distinct energetic transition states determined by the fault vectors after the Shockley partials sweeping the IDL. Furthermore, significant variations in critical resolved shear stress (CRSS) required for the super-edge dislocation to move past the IDL were observed, attributed to various sizes and faulted vectors of enclosed superlattice planar faults in the IDLs. The current study extends the existing dislocation-IDL interaction theory from pristine FCC to $L{1}_2$ lattice, advances the understanding of irradiation hardening effects in $L{1}_2$-$N{i}_3$Al, and suggests potential applicability to other $L{1}_2$ systems.