Glass-forming ability, structure and magnetocaloric effect in Gd-Sc-Co-Ni-Al bulk metallic glasses

Abstract

Magnetic cooling is one of the modern eco-friendly technologies, the development of which requires a search for novel functional materials. Gd-based metallic glasses are of promising candidates to be solid-state refrigerants, while their magnetic properties are still far from optimal. Recent studies reveal that the magnetocaloric characteristics of these alloys are correlated with their glass-forming ability (GFA). The partial replacement of the alloy components by elements that are chemically similar but strongly dissimilar in radii seems to be a very perspective way to improve GFA. This study is intended to prove how atomic size misfit influences on glass-formation, structure, and magnetic properties of Gd-based alloys on the example of Gd-Sc-Co-Ni-Al system. By gradually replacing Gd by Sc and Co by Ni, we have fabricated a series of completely glassy alloys and examine their structure, thermal characteristics, magnetic and magnetocaloric properties. We perform ab initio molecular dynamics simulations of the melts, which suggest that GFA of the alloys is mainly due to the high diversity of interatomic bond lengths. On the microscopic level, the main effect of the element substitution is the shortening of interparticle distances between rare-earths and transition metals because of strong chemical interaction.