Production of Ti–6%Al–7%Nb alloy by powder metallurgy (P/M)

The Ti–6%Al–7%Nb alloy, with α+β microstructure, was commercially developed aiming the replacement of Ti–6%Al–4%V alloy in the manufacture of surgical implants, taking into account of its enhanced biocompatibility. The processing of this alloy using powder metallurgy allows the preparation of parts with complex geometry, probably less expensive. Samples of this alloy were obtained from uniaxial hot pressing of the elemental powders in vacuum. The pressing was carried out in temperature range 1000–1500°C with pressures from 10 to 25 MPa. The influence of the processing parameters and chemical composition of the elemental powders on the final microstructure was investigated. The alloy was characterised using a scanning electron microscopy (SEM), X-ray diffraction, Vickers microhardness measurements, chemical composition determination and density measurement. The results show high densification, homogeneous chemical composition, high tensile strength and a Widmanstätten-like microstructure. The process parameters were defined aiming to reduce the interstitial pick-up (O, N, C) and to avoid grain growth during hot pressing.