Variation of microstructural features on the tensile property and corrosion resistance of Zr-Sn-Nb-Fe-Cu alloy

Highlights: • Dislocation cells and sub-grains formed by β-quenching and 480 °C/5 h heat treatment • Yield phenomenon is found in samples by 550 °C/5 h heat treatment. • Work hardening is obtained by β-quenching and subsequent annealing at 480 °C/5 h. • The dislocation strengthening plays a significant role on tensile properties. • Poor corrosion resistance is obtained due to lots of defects existed in samples. -- Abstract: Zr-Sn-Nb-Fe-Cu alloy was processed by two kinds of heat treatment and different microstructures were obtained. We focus on the effect of microstructure variation on the tensile properties and corrosion resistance. Results found that all specimens annealed at 550 °C/5 h (group A) could induce complete recrystallized structure, while dislocation cells and sub-grains formed after β-quenching and subsequent annealing at 480 °C/5 h (group B). Meanwhile, the average size and density of second phase particles (SPPs) for group A were slightly higher than that for group B. The tensile test results indicated that the yield phenomenon with distinct upper and lower yield points in tensile curves is observed due to the complete recrystallized structure with little dislocations in group A. For group B, however, the direct work hardening behavior was obtained at the initial deformation due to the interaction of existing dislocations with GBs and SPPs. The samples in group B showed a significant improvement in yield strength (YS), with a medium loss in plasticity compared with that for group A. The multiple strengthening contributions to YS mainly originate from the combination of grain refinement and dislocation. Theoretical analysis results found that the dislocation strengthening exhibited a significant effect on the tensile properties. Autoclave corrosion test indicated the specimens for group B possessed a relatively worse corrosion resistance. It was attributed to the higher O ion diffusion rate in defects and more vacancies or dislocations produced in the oxide of group B.