Superplasticity of Ti-6Al-7Nb alloys with different initial microstructures processed by high-pressure torsion

Abstract. Ti-6Al-7Nb alloy was quenched below and above the β-phase field processed by high-pressure torsion (HPT) to produce different grain sizes in ultra-fine range. The influence of temperature strain rate over superplastic properties, activation energy sensitivity were evaluated high tensile tests. mechanical properties complemented with Vickers microhardness measurement heat treated HPT-processed samples. crystallographic analysis performed through XRD EBSD studies grip tip specimens. Microhardness measurements show significant hardening respect imposed after HPT. Meanwhile, elongation 1200% accomplished at 850 °C a 2x10-3 s-1. failed specimens suggest that part exhibited dynamic recrystallization during test, which produced larger size ~5.1 µm higher fraction β phase 3.7%, under static recrystallization, attained ~3.4 3.3% fraction.