Novel Method for Making Biomedical Segregation-Free Ti-30Ta Alloy Spherical Powder for Additive Manufacturing

Ti-Ta alloys offer a good combination of high strength and low modulus among Ti-based alloys, and are ideal for biomedical applications. However, making Ti-Ta alloys has always been challenging because they tend to suffer from compositional segregation during melting due to the large difference between the melting points of Ti and Ta. This article describes a novel process for making spherical Ti-30Ta alloy powder through a unique powder metallurgy technique, namely the granulation–sintering–deoxygenation process. The results indicate that the compositional segregation problem can be overcome using this process technology. Combined with use of a deoxygenation process, the critical interstitial element, oxygen, can be controlled to < 400 ppm for powder with particle size < 75 µm. The destabilization effect of Ta on Ti-O solid solutions, and the resulting improved deoxygenation process for Ti-Ta, are discussed, as well as the phase composition and microstructure of the powders.