Liss, K.-D., Whitfield, R.E., Xu, W., Buslaps, T., Yeoh, L.A.,…, Xia, K. (2010). In situ synchrotron high-energy X-ray diffraction analysis on phase transformations in Ti–Al alloys processed by equal-channel angular pressing. Journal of Synchrotron Radiation, 16(6), 825-834.
Permanent Research Commons link: http://hdl.handle.net/10289/4124
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.