Thermal effects on the mechanical, electrochemical, and surface properties of a Ti–20Zr–5Ta–2Ag alloy for potential industrial and biomedical applications

Thermal treatment plays a key role in enhancing the surface, mechanical, and electrochemical properties of advanced alloys, enabling their application in challenging environments. This study investigates the effects of thermal treatment on the Ti-20Zr-5Ta-2Ag high-entropy alloy (HEA), a material originally developed for biomedical applications with potential for broader industrial use. The alloys were fabricated by melting the metals in a levitation furnace with a cold crucible. Disk-shaped samples were annealed at 300°C, 500°C, and 800°C in air for two hours each, followed by air cooling. Their properties were characterized using atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and electrochemical analyses. Key findings include a 50% increase in surface roughness at 300°C compared to the control, followed by a 7% increase at 500°C, and a six-fold increase at 800°C. Hardness increased by 14% (from 232 HV to 264 HV) at 300°C and 18% (to 274 HV) at 500°C, demonstrating enhanced mechanical performance at intermediate temperatures. Corrosion resistance improved significantly at 300°C, with the current density (J corr ) decreasing by 72% compared to the control. At 500°C, J corr decreased by approximately 27% compared to the control, while at 800°C, J corr surged more than 30 times indicating severe degradation in corrosion resistance. These results demonstrate that intermediate thermal treatments (300–500°C) optimize surface and electrochemical properties, paving the way for enhanced performance in biomedical implants and other demanding applications.