Ultrafast High-Temperature Sintering (UHS) of Ti and TiNb Alloys

Ultra-high temperature sintering (UHS) is an innovative process that rapidly heats materials, allowing for high densification and phase transformation within seconds. Initially developed for ceramics, fundamental research has been started recently to apply UHS for rapid sintering of metals as well. This study explores the UHS sintering of titanium and Ti-20Nb alloy starting from elemental powders. The effects of UHS current and dwell time on the microstructure, phase composition and hardness were analyzed. A densification up to 85% was achieved within a sintering time of only 120 s. The formation of β phase was observed in Ti-20Nb parts. As expected, the amount of β phase increased with higher current and dwell time caused by the accelerated interdiffusion of Ti and Nb. Furthermore, a thin titanium carbide layer was formed on the Ti and Ti-20Nb surface because of carbon diffusion from the carbon felt used during UHS. This layer could be removed by surface polishing. The study demonstrates that UHS can densify Ti and TiNb parts in seconds, yielding microstructural characteristics similar to those produced by conventional sintering methods. UHS shows promise for rapid sintering in additive manufacturing of titanium, potentially speeding up the development and production of metals alloys.