Abstract
In order to reduce the costs of powders in MIM processing, a mixture of 80% Hydride-Dehydride (HDH) Ti-6Al-4V powder with high oxygen content (4200 µg/g) and 20% gas atomized Ti-6Al-4V powder with 1600 µg/g oxygen was investigated. Particle size of both powders was < 45 µm. Tensile test specimens were produced by MIM, using 12 wt.% binder. Residual porosity after sintering for two hours at 1400 °C was only 1.2%. Due to the high oxygen content of the powder mixture, the specimens achieved high strength (YS: 889 MPa, UTS: 994 MPa) but low ductility (4.5%). By addition of 0.5 wt.% yttrium powder with a particle size < 45 µm to the powder mixture, corresponding scavenging of oxygen resulted in increase of ductility to 13.5% while the ultimate tensile strength decreased to 939 MPa, which is a still high value for as sintered MIM-processed Ti-6Al-4V. The residual porosity increased to 1.9%.
