Observation of simultaneous operation of deformation twins in both α and β phases in metastable β titanium alloy

Abstract

A powder metallurgy processed metastable Ti-10V-3Fe-3Al alloy is thermo-mechanically processed for obtaining two phase (α and β) microstructure. Subsequently, the alloy is compressed up to 0.4 (true) strain. Deformation mechanisms of the compressed sample are then thoroughly investigated. Stress-strain curve uniquely displays double yielding with serrated flow that are characteristics of formation of deformation twins, martensite in the constituent phases. In α phase, {1̅011}〈1012̅〉α deformation twin is found to be operative. In β phase, {112}〈111〉β twin with stress-induced α″ martensite are formed. For the first time, a simultaneous operation of twinning in both β (bcc) and α (hcp) is noticed in a titanium alloy. α″ martensite layer formation at β/α interface is also observed. These operational mechanisms have been discussed based on the β phase stability and atomic movement in (11̅01) planes of α phase. These results will greatly benefit in designing in new titanium alloy with desired mechanical properties.