Abstract:The rare earth (RE) element Y was added to binary Ti-48% Al(mole fraction) alloy by induction skull melting. The element Y was added individually 0.5%. The influences of rare earth metal Y on microstructure of as-cast TiAl based alloy was studied by XRD, SEM, EMPA and TEM measurement methodology. The results show that most of rare earth-rich phases (AlY) are uniformly distributed along the 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 spacing of as-cast TiAl based alloy samples. The grain size of Ti-47Al-1.2Ce alloy reaches 30-80μm, and the lamellar spacing is less than 200nm.

Key words: TiAl based alloys; thermodynamics; rare earth; microstructure