LAUSR

Abstract Molecular dynamics (MD) simulations were performed to explore the structures, energies and tensile properties of grain boundaries (GBs) as well as crack nucleation in nickel nanolaminated (Ni NL) structures. Four typical textures observed in experiments (Liu et al., 2013) [6] were considered in this paper. Results showed that low-angle GBs consist of a series of periodically arranged dislocations while high-angle GBs are composed of disordered phase for all textures. GB energies increase linearly with increasing misorientation in the range of low-angle GBs (0–10°). Then, the growth rate of energies slows down and finally stabilizes when the misorientation angle reaches 30°. Among four textures, {1 1 1} 〈1 1 0〉 texture has the highest GB energy while {1 1 0} 〈1 1 1〉 texture the lowest one. The tensile properties of NL structures with different textures and misorientations were further investigated. Results showed that the tensile properties depend primarily on textures, while weakly on GB energies and dislocation densities. {1 1 1} 〈1 1 2〉 texture possesses the best combination of high-strength and ductility among the four textures. Furthermore, the evolution of dislocation density and structure as well as the nucleation of crack were analysed. Crack nucleates at the junction between Shockley partial dislocations and twin boundaries generated during deformation for low-angle GBs, while at the location where Shockley partial dislocations and the original disordered GBs intersect for high-angle GBs. Our results provide a fundamental understanding of GB structures and deformation mechanisms of Ni NL structures.