The phase transformation and microstructure evolution during heating of Ti₂Al-Nb-based alloys

In this paper , the phase transformation and microstructure evolution during heating of TU AlNb-based alloy have been investigated by a dilatometry , Xray diffraction and scanning electron microscopy. Results show that phase transformation in Ti₂AlNb-based alloy during heating included four stages , B2 + α2→O , O→B2 , O→α2 and α2→B2. Accordingly , the expansion rate is approximate to linear , and then the dilatation law was a slight increase and at last becomes a constant. With proceeding of heating from lower temperature , O lamellar immerges in B2 matrix , and then transforms to α2 , and finally α2 particles diminish in B2 matrix.