A molecular dynamics study of mechanical properties of bioinspired functionally graded Cu-Ni alloy

Abstract

ABSTRACT Inspired from natural materials, functionally graded materials (FGMs) with gradual variations in their compositions and microstructures have drawn considerable attention in structural materials design to achieve superior stiffness, strength, and toughness. Taking Cu-Ni alloy as a representative model system, herein, we systematically explore the mechanical properties of Cu-Ni FGMs with varying Ni distributions and Ni contents, respectively, where the lattice constant of Cu-Ni FGMs is found to decrease with increasing Ni content. By carrying out uniaxial tension and compression, it is observed that Young’s modulus of Cu-Ni FGMs is nearly independent of the atomic distribution profile but sensitive to the Ni content. Yield stress also shows the strong dependency of Ni content; under the same Ni content, however, due to the sharpness of the interface and different deformation mechanisms, the yield stress becomes sensitive to the Ni distribution. Remarkably, there exists a tension-compression (T-C) asymmetry in Cu-Ni FGMs – the T-C asymmetry of yield stress is more heavily influenced by Ni distribution and content compared to Young’s modulus. Our study provides fundamental insights into the mechanical response of Cu-Ni FGMs with varying Ni distribution profiles and contents from an atomic perspective, aiding in the computational design of FGMs.