Phase Transformation in TC6 Titanium Alloy during Heating and Cooling

By means of rapid water cooling to retain the microstructure state at high temperature, the phase transformation in TC6 titanium alloy during heating and cooling processes within the two phase field was investigated. The results show that with increasing the temperature during the heating process, the secondary alpha dissolves within a range of temperature between 700 and 850 degrees C but the primary alpha dissolves at 900 degrees C. The results of energy spectrum analysis show that Al element concentration in primary alpha is higher than that in secondary alpha, that is to say, primary alpha is more stable than secondary alpha at high temperature. During the cooling process, the primary alpha grows up preferentially at a higher temperature, while due to the formation of secondary alpha through nucleation and growth, it precipitates at a relatively lower temperature, and the secondary alpha precipitates can slow down the growth of the primary alpha. Furthermore, with reducing the holding temperature, the precipitation temperature of secondary alpha gradually decreases.