Formation of novel β-Ti martensites in Ti–6Al–4V under an electric-current-pulse heat treatment

Through a rapid-heating, i.e., an electric-current-pulse treatment, new nanometer-sized lamellar β-Ti was produced in Ti–6Al–4V, originally with the fully equiaxed α-Ti and intergranular β-Ti phases. By means of orientation relationship analysis, X-ray elemental mapping and invariant-plane strain theory, the formation of such β-Ti phase is attributed to a diffusionless martensitic transformation induced by the rapid-heating. The novel lamellar β-Ti martensite presents higher hardness when compared with other structures of Ti–6Al–4V.