Interface-related deformation phenomena in metallic glass/high entropy nanolaminates

Abstract

The deformation behavior of metallic glass (MG)-high entropy alloy (HEA) nanolaminate is explored through molecular dynamics simulations using nanolaminate models of FeCoCrNiAl1.7 MG and FeCoCrNiAl0.5 HEA. Quantitative analysis of the atomic strain and dislocation dynamics among competing and cooperative deformation mechanisms is accomplished through the implementation of uniaxial tensile deformation. The combination of glassy and crystalline nanolayers biases the plastic deformation to regions near the glass-crystalline interface at lower strains, which lowers the activation barrier for the onset of dislocation nucleation and propagation. With increasing applied strain, dislocations are absorbed into the amorphous plate via slip transfer across the glass-crystalline interface, in turn triggering the activation of homogeneously distributed shear transformation zones (STZs) in amorphous plate. The competitive deformation mechanism suppresses the formation of localized shear bands and increases the resistance to dislocation motion, thereby promoting enhanced ductility in MG-HEA nanolaminates. Additionally, due to the high strength of the HEA, the laminate structures exhibit a much higher strength than conventional MG-crystalline laminates. The combination of high strength HEAs and MGs and the complex deformation behavior may overcome the typical strength-ductility trade-off and make MG-HEA laminates promising candidates for a variety of structural and functional applications.