The alloy system based on the nominal composition Ti–25AI was first studied over 30 years ago, and has undergone research for approximately the past 15 years. However, only during the past 6 years has this system been open for general public disclosure of previous government research in this area, this has lead to a deluge of research results across the world. This review covers those results as they pertain to the α2 alloy system based on Ti–AI–Nb. The complicated phase transformation sequences and stabilities for this alloy system are addressed. Furthermore, dislocation behaviour in both single phase α2 and dual phase α2 β/B2 is described. Finally, the correlation of microstructure and dislocation behaviour with tensile and fracture properties is presented.
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