Impact of annealing on structural and corrosion resistance properties of Ti20Zr20Hf20Be20Ni20 high-entropy metallic glass

Abstract

This study comprehensively investigates the effects of annealing on the structural, electrochemical properties and passivation film characteristics of Ti₂₀Zr₂₀Hf₂₀Be₂₀Ni₂₀ (at%) high-entropy metallic glass (HE-MG). Subjected to various annealing temperatures, the samples were analyzed in a 3.5 wt% NaCl solution to evaluate changes in their microstructure and assess their corrosion resistance. Findings reveal that the HE-MG undergoes multistage crystallization, displaying an amorphous matrix integrated with face centered cubic (FCC) and Ni₇Zr₂ phases between 420 and 500 °C, indicating robust thermal stability. Electrochemical assessments identify a critical temperature threshold: Below the glass transition temperature (T_g), the HE-MG maintains excellent corrosion resistance, promoting stable passivation layers. Above T_g, enhanced long-range atomic rearrangement during relaxation increases passivation layer defects and significantly diminishes corrosion resistance. X-ray photoelectron spectroscopy (XPS) analyses show that the primary components of the passivation layer are TiO₂, ZrO₂, HfO₂ and BeO. Increased annealing temperatures lead to enhanced Be and Ni content and decreased Ti, Zr and Hf. Additionally, high mixing entropy and significant atomic size mismatch suppress long-range atomic rearrangement and crystallization. The crystallization begins above T_g by 20 °C, with crystalline phases evenly distributed within the matrix without drastically affecting corrosion resistance. This investigation highlights the impact of thermal treatment on the properties of HE-MG, contributing valuable insights into optimizing their performance and applications.

Graphical abstract