Effect of rate on the deformation properties of metastable β in a high Sn content zirconium alloy

The quaternary zirconium alloy, Zr-3.5Sn-0.8Mo-0.8Nb, has shown promise as a possible system for utilization of transformation-induced plasticity. In this study, we investigate the effect of strain rate and stress-relaxation on the β→α phase transformation at room temperature, and present a technique to characterize the thermally-activated deformation of component phases of multi-phase alloys. The apparent activation volume of the α phase of this alloy is 13–18b3, in agreement with previous studies on α-zirconium alloys, while the β phase has an apparent activation volume of 80–150b3. The deformation-induced phase transformation is observed to occur more readily at lower strain rates, due to a higher strain-rate dependence than dislocation slip. This effect may lead to enhanced resistance to necking in this alloy during forming operations. •Phase transformation occurs more rapidly at lower strain rates.•Strain rate sensitivity of multiple phases is measured simultaneously and distinctly.•Macroscopic activation volume is dominated by the phase with the lowest value.•Deformation-induced phase transformation has no impact on apparent activation volume.•A novel method for measurement of strain by x-ray beam attenuation is presented.