Effluence of Tensile Deformation at Different Test Temperature on Microstructure of the Ti-24Al-14Nb-3V-0.5Mo Alloy

초록

Microstructure of the Ti-24Al-14Nb-3V-0.5Mo (at %) alloy deformed from room temperature to 700 deg.C was studied by the H-800 transmission electron microscope (TEM) equipped with a side entry goniometer stage capable of 45 tilt on the X or Y axis operating under two-beam condition. Especially dislocation types and slip systems of the 2-phase (D019) were analyzed in accordance with invisibility criterion. The results indicate that with increasing the deformation temperature from room temperature to 700C, the slip of -type dislocations on prismatic planes { } in the 2-phase is enhanced, while that on basal planes (0001) with hexagonal morphology is weakened after the alloy is tensioned with a 3% tensile strain. Refined microstructure is related to the sub-grain which originates from high-temperature deformation and recovery, and precipitates of the secondary acicular 2 phase from the matrix of B2 phase and O phase from the primary equiaxed 2 phase. When the test temperature is increased to 700C, the slip of + /2-type dislocation on pyramidal planes { } is also observed, but the hexagonal dislocation networks formed by the slip of -type dislocations on basal planes are hardly seen.