TENSILE　DEFORMATION　AND　FRACTURE　BEHAVIOR　OF　Ti_3Al-Nb　ALLOY　AT　HIGH　TEMPERATURE

ＴＥＮＳＩＬＥＤＥＦＯＲＭＡＴＩＯＮＡＮＤＦＲＡＣＴＵＲＥＢＥＨＡＶＩＯＲＯＦＴｉ３ＡｌＮｂＡＬＬＯＹＡＴＨＩＧＨＴＥＭＰＥＲＡＴＵＲＥ①ＷｕＹｉｎｇ，ＺｈｅｎＬｉａｎｇ，ＹａｎｇＤｅｚｈｕａｎｇＳｃｈｏｏｌｏｆＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅａｎ...

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 α 2 and B 2 phases, which make the grain finer; the α 2/α 2 and α 2/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 α 2 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 , δ are 685 MPa, 580 MPa, 12.5% respectively.