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

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 degrees 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 degrees 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.