The effect of lanthanum on the microstructure and high temperature mechanical properties of a beta-solidifying TiAl alloy

The effect of lanthanum (La) on the microstructure and high temperature mechanical properties of Ti-43.5Al-4Nb-1Mo-0.1B alloy was examined by high temperature compression tests, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The results showed that the volume fraction and the mean size of dispersed oxide particles were increased with increasing La content. Besides, a small amount of La-addition was effective in improving the peak flow stress, particularly for 0.2 at.% La-added specimen, showing 14% and 44% enhancement at 900 and 1000 °C, respectively. The microstructure of hot deformed samples also indicated that small and closely spaced oxide particles had retarding effect on dynamic recrystallization.