Effect of rare earth on microstructure of γ-TiAl intermetallics

The rare earth (RE) elements (Ce, La) were added to binary Ti-47% Al alloys (atomic fraction) by Induction Skull Melting. The element Ce of 1.0 atomic percent was added individually, and La of 0.2 atomic percent was added individually. This article studied the influences of rare earth metal (Ce, La) on microstructure of as-cast TiAl based alloy by XRD, SEM, EMPA and TEM measurement methodology. The results show that most of rare earth-rich phases (AICe, Al-La) are uniformly distributed in grain boundary in the shape of discontinuous network, and some particles of rare earth-rich phases within the grains are mainly ellipsoids. In addition, rare earth element can obviously refine the grain size and the lamellar thickness of as-cast TiAl based alloy samples. The grain size of Ti-47Al-l.0Ce-0.2La alloy reaches about 30-80 μm, and the lamellar thickness of its γ phase and α₂ phase are less than 200 and 20 nm, respectively.