Absence of a pressure-induced structural phase transition in Ti3Al up to 25 GPa - art. no. 024106

Experimental high-pressure studies of titanium aluminide (Ti,AI) have been carried out under quasihydrostatic and nonhydrostatic conditions up to a pr essure of 25 GPa using an in situ powder x-ray diffraction technique. The e xperiments were complemented by first-principles total energy calculations. The experimental equation of state for three samples with different compos itions was fitted using the Birch-Murnaghan equation. The obtained paramete rs agree very well with theoretical results, in the studied pressure range neither experiment nor theory observed any pressure-induced structural phas e transition. In particular, the phase transition from the DO19 (Ni3Sn type ) structure of Ti3Al to DO24 (Ni3Ti type) structure, reported earlier by Sa hu et nl. [Phys. Rev. Lett. 78, 1054 (1997)] is not confirmed in our study. Possible reasons for the discrepancy are analyzed.