Preparation of the ZrTiAlV alloy with ultra-high strength and good ductility

The 30Zr–62Ti–5Al–3V (wt%) alloy with ultra-high strength and good ductility was prepared via consumable electro-arc melting, forging, and heat treatment. The phase transition and structure evolution of the alloy during heat treatment were also investigated. X-ray diffraction (XRD) results show an orthorhombic martensite α′′ phase in the specimen solution-treated at 825 °C. The orthorhombic martensite α′′ phase decomposed into α and β phases during the subsequent ageing treatment. No intermetallic compound peak was found in the XRD patterns of the specimens under different conditions. Microstructural analysis shows that the fine short-bar-shaped α phase precipitated along the original β grain boundary together with the ultrafine dot-shaped α phase that presented inside the original β grain when the ageing temperature was lower than 550 °C. As the ageing temperature increased, the dot-shaped α phase inside the original β grain gradually grew into the short-bar shape. The different microstructures resulted in varied mechanical properties. After ageing at 500 °C, the tensile strength reached 1622 MPa; at the same time, the 2.1% ductility in terms of elongation was retained. As the ageing temperature increased to 650 °C, the ductility (in terms of elongation) increased to 9.3% and the strength remained above 1400 MPa. The ultra-high strength and good ductility of the studied alloy make it a good candidate for a wide range of applications.

► Ultra-high strength 1622 MPa together with good ductility was realized. ► The α″ phase was detected in the solution treated speciment. ► The α″ phase only decomposed into α and β phase but no intermetallic compound. ► The microstructure is characterized by dispersive and fine α phase in β matrix.