Quantitative analysis of microstructure and deformation mechanisms during isothermal compression of Ti–5Al–5Mo–5V–1Cr–1Fe alloy

• Few DRX α grains appear in the α + β phase region.
• DRX occurs in the β phase region and raises with increasing strain rate.
• α phase deforms less than β matrix at medium temperatures and lower strain rates.
• Acicular α is not observed at higher temperatures and lower strain rates.

The effects of the processing parameters on the grain size and volume fraction of equiaxed α for Ti–5Al–5Mo–5V–1Cr–1Fe are quantitatively investigated using isothermal compression tests. The microstructure features, such as the morphology of equiaxed and acicular α phase, the dislocation distribution, the formation of substructure are in depth discussed with the help of transmission electron microscopy (TEM) and scanning electron microscopy (SEM) experiments so as to clarify the deformation mechanisms. The results show that few DRX α grains appear in the α + β phase region. In the β phase region, selective DRX occurs and the amount of DRX increases with increasing strain rate. DRV is main softening mechanism in the tested deformation temperature range. The elongated β grains are observed at medium deformation temperatures and lower strain rates. This phenomenon demonstrates that β phase is mainly involved in the deformation. At higher deformation temperatures and lower strain rates, acicular α is not observed for this alloy. Possible reason is that acicular α dissolves into the β matrix.