Optimization of processing parameters to produce nearly dense fine-grained Ti–6Al–4V microstructures with a hydrogen-assisted BEPM approach

Abstract

Abstract In the present study, fine-grained and nearly dense Ti–6Al–4V alloy is produced by press-and-sinter blended elemental powder metallurgy using titanium hydride powder. Methods to produce a desirable alloy microstructure at a relatively low ( 1100 °C ) sintering temperature are developed, including thermocycling around the α ↔ β transus temperature and hydrogenation–dehydrogenation of powder compacts at 850 °C to realize the alpha-beta phase transformations. The associated volume changes promote acceleration of diffusion and enhanced densification. A sintering regime combining these two treatments incorporates their respective advantages of retarded grain growth and improved densification during sintering at 1100 °C . The fine grain size (~45 μm), acceptable oxygen content (0.17%–0.21%), and reduced residual porosity (~2%) of the as-sintered Ti–6Al–4V provide tensile characteristics (880 ± 20Mpa of UTS, 15 ± 2% of Elongation) suitable for practical application.