Microstructure and Mechanical Properties of a New RefractoryHf۹.۳Nb۱۸.۹Ta۳۴.۷Ti۳۲Zr۵.۱ High Entropy Alloy at Room Temperature

Refractory high entropy alloys (RHEAs) have garnered significant attention in materialsscience over the past two decades due to their unique combination of high strength and stability atelevated temperatures, including wear resistance and high temperature (HT) compressive strength.Equiatomic HfNbTaTiZr RHEA has attracted interest for its favorable ductility and HT strengthcompared to nickel-based superalloys. However, its yield strength (YS) at room temperature (RT)remains relatively low. In this study, the 𝐇𝐟𝟗.𝟑𝐍𝐛𝟏𝟖.𝟗𝐓𝐚𝟑𝟒.𝟕𝐓𝐢𝟑𝟐𝐙𝐫𝟓.𝟏 RHEA is introduced andexamined, demonstrating higher strength and ductility at RT compared to the equimolar alloy. Thealloy was synthesized in a vacuum arc remelting furnace using alloying elements with ۹۹.۹% purity.Phase transformation studies followed, involving homogenization at ۱۲۰۰°C for ۲۴ hours with acooling rate of ۱۰°C per minute down to ۵۰۰°C, followed by air cooling. Microstructural analysis wasconducted using optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction(XRD) for phase identification and analysis of the alloy and the oxide layer formed duringhomogenization. Results indicated that the alloy exhibits a bcc matrix, B۲ precipitates, and an hcpphase in its homogenized state. The hardness of the homogenized specimen was ۵۰۳ Vickers, with acompression YS of ۱۲۵۴ MPa and ductility of ۳۰% at RT.

کلیدواژه ها:

Ductile ، Room temperature ، Refractory high entropy alloy ، Ordered B۲ phase