Synthesis and characterisation of Ti6Al4V/xTa alloy processed by solid state sintering

ABSTRACT

This work investigates the effect of Ta particle addition into a Ti6Al4V alloy processed by solid state sintering. The volume fraction of Ta ranged between 0 and 30?vol.-%. The sintering kinetics of powder mixes are evaluated by dilatometry. Sintered materials are characterised by SEM and XRD, and their mechanical properties are obtained from microhardness and compression tests. Sintering behaviour and final microstructure are affected by Ta particles, which slow down the densification, lower the temperature of α-to-β phase transition and stabilise the β phase. Mechanical properties, as microhardness, Young’s modulus and yield stress, depend on the microstructure reached after sintering and on the residual porosity. An equation expressing the Young’s modulus of Ti6Al4V/xTa alloy as function of x and porosity is proposed and validated. The materials with at least 20?vol.-% of Ta exhibited a high strength to modulus ratio, which is suitable for orthopaedic implants.