A novel Zr-based alloy microstructure with high strength and excellent ductility

Abstract

This paper reports the structural evolution and mechanical properties of a Zr98.2Cr1.8 (denoted by at%) alloy during, including hot rolling (HR), solution treatment (ST), and solution and ageing treatment (STA). X-ray diffraction (XRD) was used to analyze the phase composition. New microstructures were discovered, such as a fully equiaxed microstructure which was produced by solution treatment, and a bimodal structure which was formed by solution and ageing treatment were discovered. Transmission electron microscopy (TEM) bright field images demonstrated that the thickness of the secondary αs phase hinges on the heat treatment methods and, while the α׳ phase exists in the sample by solution treatment at 900°C. The fully equiaxed microstructure renders the alloy with a high ultimate tensile strength of 1109MPa and a ductility of 10.9 while the bimodal microstructure renders the alloy with an ultimate tensile strength of 818MPa and an excellent ductility of 18.4 through STA at 750°C. Moreover, the value of the alloy strength with different heat treatments was consistent with the increasing tendency of the lattice distortion.