Remarkable Enhanced Mechanical Properties of TiAlCrNbV Medium-Entropy Alloy with Zr Additions

Most medium entropy alloys (MEAs) exhibit excellent mechanical properties, but their applications are limited because of their high density. This study explores a series of lightweight nonequiatomic Ti-65(AlCrNbV)(35-x)Zr-x (x = 3, 5, 7, and 10) MEAs with a low density, high strength, and high ductility. To achieve solid solution strengthening, Zr with a large atomic radius was used. In addition, various thermomechanical treatment parameters were adopted to further improve the MEAs' mechanical properties. The density of the MEAs was revealed to be approximately 5 g/cm(3), indicating that they were lightweight. Through an X-ray diffraction analysis, the MEAs were revealed to have a single body-centered cubic structure not only in the as-cast state but also after thermomechanical treatment. In terms of mechanical properties, all the as-cast MEAs with Zr additions achieved excellent performance (>1000 MPa tensile yield strength and 20% tensile ductility). In addition, hot rolling effectively eliminated the defects of the MEAs; under a given yield strength, hot-rolled MEAs exhibited superior ductility relative to non-hot-rolled MEAs. Overall, the Ti-65(AlCrNbV)(28)Zr-7 MEAs exhibited an optimum combination of mechanical properties (yield strength > 1200 MPa, plastic strain > 15%) after undergoing hot rolling 50%, cold rolling 70%, and rapid annealing for 30 to 50 s (at a temperature of approximately 850 degrees C) with a heating rate of 15 K/s. With their extremely high specific yield strength (264 MPa.g/cm(3)) and high ductility (22%), the Ti-65(AlCrNbV)(28)Zr-7 MEAs demonstrate considerable potential for energy and transportation applications.

Automated summary

This study explores the use of lightweight nonequiatomic MEAs with Zr additions to achieve high strength and high ductility properties. The Ti-65(AlCrNbV)(28)Zr-7 MEAs demonstrated an optimum combination of mechanical properties after undergoing hot rolling, cold rolling, and rapid annealing. With their high specific yield strength and ductility, these MEAs have considerable potential for energy and transportation applications.