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 beta-Ti was produced in Ti-6Al-4V, originally with the fully equiaxed alpha-Ti and intergranular beta-Ti phases. By means of orientation relationship analysis, X-ray elemental mapping and invariant-plane strain theory, the formation of such beta-Ti phase is attributed to a diffusionless martensitic transformation induced by the rapid-heating. The novel lamellar beta-Ti martensite presents higher hardness when compared with other structures of Ti-6Al-4V. (c) 2006 Elsevier B.V. All rights reserved.