Absence of a pressure-induced structural phase transition in ${\mathrm{Ti}}_3\mathrm{Al}$ up to 25 GPa

Experimental high-pressure studies of titanium aluminide $\left({\mathrm{Ti}}_3\mathrm{Al}\right)$ have been carried out under quasihydrostatic and nonhydrostatic conditions up to a pressure of 25 GPa using an in situ powder x-ray diffraction technique. The experiments were complemented by first-principles total energy calculations. The experimental equation of state for three samples with different compositions was fitted using the Birch-Murnaghan equation. The obtained parameters agree very well with theoretical results. In the studied pressure range neither experiment nor theory observed any pressure-induced structural phase transition. In particular, the phase transition from the ${\mathrm{DO}}_{19}$ $({\mathrm{Ni}}_3\mathrm{Sn}$ type) structure of ${\mathrm{Ti}}_3\mathrm{Al}$ to ${\mathrm{DO}}_{24}$ $({\mathrm{Ni}}_3\mathrm{Ti}$ type) structure, reported earlier by Sahu et al. [Phys. Rev. Lett. 78, 1054 (1997)] is not confirmed in our study. Possible reasons for the discrepancy are analyzed.