Deformation Behavior of Dual-Phase LTSP Ti3Al Based Alloy

Abstract

Ti3Al based alloys have been widely reported for their admirable superplasticity in the temperature range of 900-1000oC. However, the superplastic behavior of temperature lower than 900oC was seldom reported. Dual phase (α2+β) Ti3Al-10Nb alloy has shown superior superplastic elongation of 1500% at 960oC and 2x10-4 s-1. In this paper, it aims to investigate the superplastic behavior at lower temperature (700-900oC). The relationship of texture characteristics, phase transformation phenomena, and deformation mechanism at lower temperature (below 900oC) are studied. The optimum low-temperature superplastic condition with an elongation of 333% was occurred at 850oC and 5x10-4 s-1. With abundant hexagonal α2’ laths formed inside the β grains, the major accommodation process via dislocation slip across the β grains is impeded. It leads to premature failure and lower tensile elongations at lower temperature. Moreover, with the minor operating of grain rotations and grain boundary sliding, the texture intensity decreases significantly at temperature 850oC.