Uniaxial deformation of face-centered-cubic(Ni)-ordered B2(NiAl) bicrystals: atomistic mechanisms near a Kurdjumov-Sachs interface

Creating tailored interfaces between soft and hard materials is a promising route to simultaneously enhance ductility and strength of multicomponent materials. Here, we study deformation mechanisms in a model bicrystal, with a Kurdjumov-Sachs (KS) interface, between face-centered-cubic Ni and ordered-B2 NiAl slabs using molecular dynamics simulations. The bicrystals were uniaxially deformed by strain rates of and by holding temperatures constant at 300, 500, 700, and 900 K for each strain rate. Our simulations reveal atomistic processes that create sessile and glissile dislocations, and their reactions during high-strain rate deformation. At strain rates, dislocation processes enhance ductility and cause large-scale atomic rearrangements in the KS interfacial region. This subsequently causes nucleation, growth, and coalescence of nano-voids into cracks inside the harder B2-ordered phase bordering the interface. Our results suggest that interfaces between "soft"-"hard" materials likely withstand high-strain rates better.