Fundamental insights into the mass transfer via full dislocation loops due to alternative surface cuts

Abstract

Mass transfer during the formation and emission of a dislocation loop without non-conservative motions can be very tricky. We combine the molecular statics, nonsingular dislocation theory, finite element (FE) method and molecular dynamics (MD) approach to offer new insights. It is proved both theoretically and numerically that the formation and the dynamic emission of a full shear loop can grow a nanovoid. For the first time, a novel approach is proposed to create a shear loop via a hemispherical surface cut by the atomistic simulation. Such a formation process can produce a similar shear loop to that via a flat surface cut, and yet lead to void growth. We incorporate the non-singular dislocation theory into a FE model to calculate the potential energy regarding different surface cuts. Among possible cuts to create a shear loop, the potential energy would favour the one that grows a void under triaxial tension. We show that the arbitrariness regarding the surface cut of dislocation segments should also be recognized during the dynamic emission process. Under triaxial tension, we confirm the mass transfer during the cross-slipping of V-shape shear loops prior to the completion of prismatic loops. By comparison, the uniaxial tension case shows that a V-shape shear loop is not necessarily the precursor of a prismatic loop. Hence, its mass transfer mechanism should be treated differently.