Study on mechanical properties of high-entropy crystal/amorphous composites with pre-existing hole

Abstract

In recent years, experiments have shown that it is possible to develop crystal/ amorphous composites (CAC) with high strength and ductility by combining high-entropy alloys and metallic glasses (HE-MGs). In this paper, the rapid solidification of CoNiCrFeMn is simulated by molecular dynamics simulations to obtain HE-MGs, and subsequently holes of different sizes were added inside it for uniaxial tension. The result indicates that the larger hole has better plasticity, but the plasticity increases at the cost of the decrease of strength and hardness. Based on the consideration of strength and plasticity, CoNiCrFeMn HE-MGs with a hole radius of 7.06 Å are selected to examine the effect of the crystal layer thickness on the mechanical properties of CAC. The different distance of the crystal/amorphous interface from the hole is due to the crystal layer thickness. And the interface disperses the localized strain to a larger area by hindering the extension of shear transformation zone, resulting in a more uniform distribution of strain and improving the strength of CAC. In addition, the interface is composed of FCC and other amorphous clusters, and there are three connection modes among them. The growth of interfacial clusters will enhance the strength of CAC. The current work helps to understand the deformation mechanisms of high-entropy CAC at the nanoscale, and may advance the development of metallic materials with a synergy of high strength and ductility.