The influence of interface shear strength on the glide dislocation–interface interactions

Interfaces with relatively low shear strengths can be strong barriers to glide dislocations due to dislocation core spreading within the interface plane. Using atomistic modeling we have studied the influence of interface shear strength on the interaction of lattice glide dislocations with fcc/bcc interfaces. “Tunable” interatomic potentials are employed to vary the interface shear strength for the same interface crystallography. The results show that: (1) the interface shear strength increases as the dilute heat of mixing decreases; (2) the interface shear mechanism involves the nucleation and glide of interfacial dislocations, which is dominated by the atomic structures of interfaces, regardless of the interface shear strength; (3) weak interfaces entrap lattice glide dislocations due to the interface shear and core spreading of dislocations within interfaces. Reverse shear displacement is needed to enable collapse of the spread core for slip transmission. This study provides an insight into the correlation between interface shear strength and glide dislocation trapping at the interface, which is a crucial unit mechanism in understanding the ultra-high strengths observed in nanoscale fcc/bcc multilayers.

Research highlights► The effects of the dilute heat of mixing on interface shear were studied using MD. ► The interactions of dislocations with interfaces were studied using MD. ► Interface shear strength increases as the dilute heat of mixing decreases. ► The weaker the interface, the larger is the extent of core spreading. ► The weaker the interface, the stronger is the attractive interaction.