New approach to achieve high strength powder metallurgy Ti-6Al-4V alloy through accelerated sintering at β-transus temperature and hydrogenation-dehydrogenation treatment

It is demonstrated that high density powder metallurgy (PM) Ti-6Al-4V alloy, with a finer prior-beta grain size, can be achieved by vacuum sintering of TiH2 compacts at the beta-transus (1010 degrees C) temperature, taking advantage of the accelerated self-diffusion. The subsequent refinement of the coarse lamellar microstructure by hydrogenation-dehydrogenation treatment produces a high tensile strength (similar to 1130 MPa) and ductile (similar to 10%) alloy. The superior tensile strength and ductility result from the nanoscale Widmanstatten structure and the finer prior-beta grain size, respectively, created by the two treatments. The results show a promising pathway to make high strength and ductile PM titanium alloys. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.