MICROSTRUCTURE EVOLUTION AND ITS EFFECT ON TENSILE AND FRACTURE-BEHAVIOR OF TI-AL-NB ALPHA(2)-INTERMETALLICS

The alloy system based on the nominal composition Ti-25Al was first st udied over 30 years ago, and has undergone research for approximately the past 15 years. However, only during the past 6 years has this syst em been open for general public disclosure of previous government rese arch in this area, this has lead to a deluge of research results acros s the world. This review covers those results as they pertain to the a lpha2 alloy system based on Ti-Al-Nb. The complicated phase transforma tion sequences and stabilities for this alloy system are addressed. Fu rthermore, dislocation behaviour in both single phase alpha2 and dual phase alpha2 + beta/B2 is described. Finally, the correlation of micro structure and dislocation behaviour with tensile and fracture properti es is presented.