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 alpha '' phase in the specimen solution-treated at 825 degrees C. The orthorhombic martensite alpha '' phase decomposed into alpha and beta 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 alpha phase precipitated along the original beta grain boundary together with the ultrafine dot-shaped alpha phase that presented inside the original beta grain when the ageing temperature was lower than 550 degrees C. As the ageing temperature increased, the dot-shaped alpha phase inside the original beta grain gradually grew into the short-bar shape. The different microstructures resulted in varied mechanical properties. After ageing at 500 degrees 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 degrees 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. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.