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 (alpha-Ti, TiAl(3)). Upon annealing, the phase evolution and lattice parameter changes owing to chemical segregation, which is in favour for the more equilibrated phases such as gamma-TiAl, alpha(2)-Ti(3)Al and TiAl(2), were followed unprecedentedly in detail. An initial delta-TiH(2) content with a phase transition at about 625 K upon heating created an intermediate beta-Ti phase which played an important role in the reaction chain and gradually transformed into the final products.
The Bragg Institute, Australian Nuclear Science and Technology Organisation, Menai, NSW, Australia. kdl@ansto.gov.au
Klaus Dieter
KD
Liss
Ross E
RE
Whitfield
Wei
W
Xu
Thomas
T
Buslaps
Lareine A
LA
Yeoh
Xiaolin
X
Wu
Deliang
D
Zhang
Kenong
K
Xia