Transition from high-entropy to conventional $(TiZrNbCu)_{1-x}Co_x$ metallic glasses

TL;DR

This study explores the transition from high-entropy to conventional metallic glasses in the $(TiZrNbCu)_{1-x}Co_x$ system, revealing compositional effects on structure, stability, electronic, magnetic, and mechanical properties.

Contribution

It provides a comprehensive analysis of how properties evolve across the composition range, highlighting the onset of magnetic correlations and changes in atomic packing.

Findings

Atomic volume deviates from Vegard's law at x≥0.2

Valence band shows split-band shape with Co 3d-states near Fermi level

Magnetic susceptibility and microhardness increase rapidly with x

Abstract

A new amorphous alloy system $(TiZrNbCu)_{1-x}Co_x$ covering a broad composition range from the high-entropy (HEA) to Co rich alloys (x$\leqslant$ 0.43) has been fabricated, characterized and investigated. A comprehensive study of the chemical compositions, homogeneity, thermal stability, electronic structure and magnetic and mechanical properties has been performed. All properties change their variations with x within the HEA range. In particular, the average atomic volume deviates from the Vegard's law for x$\ge 0.2$, where also the average atomic packing fraction suddenly changes. The valence band structure, studied with ultraviolet photoemission spectroscopy, shows a split-band shape with 3d-states of Co approaching the Fermi level on increasing x. Due to onset of magnetic correlations magnetic susceptibility rapidly increases for x$\ge 0.25$. Very high microhardness increases rapidly with x. The results are compared with those for similar binary and quinary metallic glasses and with those for Cantor type of crystalline alloys.