Multiscale study on the tensile fracture of Al-terminated Cu(1 1 1)/α-Al₂O₃(0 0 0 1) interfaces

Based on a kind of pair potential function describing the interaction across the sapphire/copper interface and Embedding Atom Method (EAM) potential for copper, the tensile mechanical properties of two kinds of Cu(1 1 1)/α-Al₂O₃(0 0 0 1) interfaces with two types of initial condition, i.e. Single-layer and Double-layers Al-terminated interface with copper atoms nearly atop Al³⁺ and two successive (over(1, ̄) 1 0) planes of copper film astride Al³⁺ and O^2- along the [over(1, ̄) over(1, ̄) 2] / [2 over(1, ̄) over(1, ̄) 0] direction, are studied by employing the quasicontinuum method. The curves of loading vs. tensile displacement are plotted and the atomistic structures at different loading stages for the two kinds of interface with the two different initial conditions are also discussed. Although it seems that in the stable area of relaxed structures for Single-layer/Double-layers Al-terminated interface copper atoms locate atop Al³⁺/O^2-, most of copper atoms rest atop O^2- for the two kinds of Al-terminated interface. Meanwhile, the location of interfacial imperfect bonding area has a tremendous influence on the deformation process and mode of interface failure. The strength of Single-layer Al-terminated interface is relatively larger than that of double-layers counterpart. The initial positions of coppers atoms have small effects on the tensile strength.