In situ synchrotron high-energy X-ray diffraction analysis on phase transformations in Ti-Al alloys processed by equal-channel angular pressing

Mixtures of 47‐Al and 53‐Ti powders (atomic %) have been consolidated using back pressure equal‐channel angular pressing starting with both raw and ball‐milled powders. In situ synchrotron high‐energy X‐ray diffraction studies are presented with continuous Rietveld analysis obtained upon a heating ramp from 300 K to 1075 K performed after the consolidation process. Initial phase distributions contain all intermetallic compounds of this system except Al, with distribution maxima in the outer regions of the concentrations (α‐Ti, TiAl3). Upon annealing, the phase evolution and lattice parameter changes owing to chemical segregation, which is in favour for the more equilibrated phases such as γ‐TiAl, α2‐Ti3Al and TiAl2, were followed unprecedentedly in detail. An initial δ‐TiH2 content with a phase transition at about 625 K upon heating created an intermediate β‐Ti phase which played an important role in the reaction chain and gradually transformed into the final products.