The ageing response of direct laser deposited metastable β-Ti alloy, Ti–5Al–5Mo–5V–3Cr

The formation of solely β-phase titanium after direct laser deposition (DLD) of metastable β-Ti alloy does not provide the desired properties. Hence, we present a study into the ageing response of DLD built Ti-5553 β-Ti alloy to obtain the bimodal (β + α) microstructure providing improved properties. The results obtained from the heat treatments showed that a unique microstructure with refined intragranular and discontinuous grain boundary α-phase can be obtained by directly ageing (using fast heating rate) the as-built samples at the ageing condition (600 °C + 0.5 h). This microstructure produced a good balance in mechanical properties (UTS = 1345 ± 5 MPa and δ = 11.6 ± 0.5%). The interparticle spacing between the α-phase (d) showed a correlation with microhardness (Hv=340+158/√d) and yield stress (σ0.2=870+15086/√d) values for all the aged samples.