Stability of the B2 Phase in Ternary Ti-Al-X Alloys (X=Nb, Mo, V)

Abstract

In the first part of this work, the β(or B2)-stabilizing effectiveness was discussed by experimentally determining the temperature dependence of equilibrium volume fraction of the β(or B2) phase as well as the variation of the β-transus temperature as a function of β-alloying additions. In the second part, the thermal stability of the B2 matrix in three inter-metallic compounds (Ti2 AlNb, Ti2 AlMo and Ti5 Al2V) was studied. Flow stress anomalies were observed in these alloys deformed in compression as the testing temperature was increased. The transition phases which appear in Ti2 AlNb and Ti5 Al2V compounds over the 650-850 K temperature range are responsible for these anomalies. Implications of such B2 decompositions on the development of this category of alloys are briefly discussed. © 1994, The Japan Institute of Metals. All rights reserved.