Abstract:As Ti ₃Al base alloys have potentials used as high temperature structural material, the tensile deformation and fracture mechanism of Ti ₂₄Al ₁₄Nb 3V 0.5Mo(mole percent) alloy at high temperature was studied. The results indicate that there are considerable subgrain boundaries in the α₂ and B₂ phases, which make the grain finer; the α₂/α₂ and α₂/B ₂ boundaries are vague and there are high density of dislocation tangles in the  B 2 phase; the slip of a type dislocations on basal planes {0001} and prismatic planes {1010} is the main deformation mode in the α₂ phase apart from a few of c+a/2 type dislocations on pyramidal planes {0221}. The fracture of samples tensioned at 700 ℃ is of dimple type, and σ_b , σ_0.2 , δare 685 MPa, 580 MPa, 12.5% respectively.

Key words: Ti ₃Al Nb alloy tensile deformation fracture