Evolution of β phase and mechanical mechanisms in an α-type Zr alloy processed by rolling at different temperatures

Abstract

Herein, the effect of deformation temperature on microstructure evolution and mechanical properties in an α-type Zr0.5Be (wt%) alloy has been discussed in detail. The results indicate that with the increase of deformation temperature, the deformation degree of α-laths is decreased. The duplex microstructure including coarse primary αp and secondary αs has been obtained in Zr0.5Be alloy deformed at 870 °C. The evolution of microstructures can be attributed to the change of deformation energy and atomic diffusion rate with the variation of temperature. The β phase appears as the deformation temperature is set to 670 °C and 770 °C. The transformation process of the β phase is caused by the combination of segregation degree and diffusion rate of Be atoms along with the deformation stored energy in the matrix. Also, as the deformation temperature is gradually increased, the tensile strength and microhardness are both decreased while the fracture elongation is increased. As the deformation temperature rises, the combined effects of the occurrence of dynamic recrystallization, elimination of deformation stored energy, and uniform distribution of Be elements can play a leading role in the increase of fracture elongation and decrease of strength.