Effects of boron on phase transformation of high Nb containing TiAl-based alloy

The effect of 0.7 at% boron on the phase transformation of Ti-46.5Al-8Nb during a range of different continuous cooling rates from the alpha single phase region has been investigated. In addition the microstructure of Ti-46.5Al-8Nb and Ti-46.5Al-8Nb-0.7B during water quenching at a range of different temperatures near the alpha transus temperature (Tα) has been examined. It has been found that the trend of the variation of microstructures with different cooling rates is the same in the two alloys varying from massive gamma (γm) to lamellar, but boron addition increases the cooling rate to obtain these microstructures. During water quenching at different temperatures (T1 ≅ Tα, T2 < Tα, and T3 ≪ Tα) boron addition has a very strong effect on the trend of the variation of microstructures.