Influence of mechanical tensile and compression tests under high strain rate on structural properties of copper monatomic metallic glass

Abstract

This paper aims to investigate the structural properties of Cu-monatomic metallic glass, and to elucidate the effect of mechanical tensile and compression tests with high strain rate on these properties. This work is performed by using molecular dynamics simulations combined with embedded atom method. The structure parameters such as radial distribution function, Voronoi Tessellation and Common neighbor analysis have been used to characterize and investigate the local structure in the Cu-monatomic metallic glass. Our numerical results show that, the most dominant structures are the distorted icosahedra ⟨0,1,10,2⟩ and ⟨0,2,8,4⟩ for this specific system. These two structures are more higher than the full icosahedra motif ⟨0,0,12,0⟩ which presents, generally, the high percentage for multi-component and for some monatomic metallic glasses. In addition, we have found that the second peak splitting in the partial distribution function of Cu metallic glass is caused essentially by the icosahedra-like polyhedron and not only by the full icosahedra. On the other hand, we have shown that the mechanical tests strongly influence these local structures. In fact, tensile and compression tests lead to reduce the importance of the short range order by decreasing the icosahedra and icosahedra-like fractions. However, these mechanical effects do not alter significantly ⟨0,3,6,4⟩ clusters, which maintain almost the same percentage during the mechanical testing. Moreover, comparison between compression and tensile tests with regard to the mechanical behavior and how it can be altered by the strain rate is done. Implications of these results are briefly discussed.