Advances in Sintering of Titanium Aluminide: A Review

Titanium aluminides (TiAl) are prominent advanced materials for aerospace and automobile industries owing to their great engineering properties conferred by ordered structures and partial covalent bonding. Of all the TiAl phases, Ti₃Al and TiAl are considered to have great engineering significance and, thus, are extensively examined and developed for elevated temperature conditions. Nevertheless, one of the impediments to the wider application of TiAl and Ti₃Al alloys is the deficit in the malleability at room temperature, creating difficulties during fabrication as it is sensitive to microcracks and highly susceptible to superficial defects. Sintering technologies such as cold pressing, cold isostatic pressing, hot pressing, hot isostatic pressing, combustion synthesis, and microwave sintering for producing advanced TiAl are presented. However, these processes have restrictions on the control of the microstructural properties and phase evolution, which inevitably affect the quality of the TiAl products. The novel spark plasma sintering (SPS) offers opportunities to circumvent challenges existing in the production of TiAl. An innovative hybrid spark plasma sintering technology with great potential for large-scale fabrication of operational materials with improved microstructural characteristics yielding exceptional product value and enhanced design autonomy is also presented as a robust alternative for sintering TiAl alloys.