TENSILE DEFORMATION AND FRACTURE BEHAVIOR OF Ti3Al-Nb ALLOY AT HIGH TEMPERATURE
(School of Materials Science and Engineering; Harbin Institute of Technology; Harbin 150001)
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 σb , σ0.2 , δare 685 MPa, 580 MPa, 12.5% respectively.
Key words: Ti 3Al Nb alloy tensile deformation fracture