Phase equilibria involving the tau-L1(2) and TiAl2 phases in the Ti-Al-Cr system

An investigation into the phase equilibria of the Al-rich portion of the Ti-Al-Cr ternary system was carried out using both bulk alloy and diffusion couple samples. Combination of the data from the samples enabled the construction of partial isothermal sections at 1000 and 800 degrees C. Further, the Ti(Cr,Al)(2) + tau --> beta(Cr) + TiAl2 invariant reaction was found to occur between 1000 and 800 degrees C. In addition to the above reaction a precursor invariant reaction, TiAl + tau --> Ti(Cr,Al)(2) + TiAl2, also occurs between those temperatures. Due to the recession of the beta(Cr) phase with decreasing temperature and the formation of the Cr2Al phase, the beta(Cr) + tau --> Cr2Al + Al8Cr5 invariant reaction was observed at about 890 degrees C. Copyright (C) 1996 Elsevier Science Limited.