Irradiation-induced structural transitions in Ti2AlC

In this study, 1 MeV Au ions were used to irradiate Ti2AlC at room temperature with fluences ranging from 1 × 1014 to 2 × 1016 cm−2. The structural transformation and the evolutions of defects induced by Au irradiation were investigated by means of Grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM). GIXRD analyses show serious structural disorder and phase transitions, which are consistent with the selected area electron diffraction (SAED) results and high-resolution TEM images. TEM observations reveal that the nanolayered structures are partially disturbed at the lowest fluence of 1 × 1014 cm−2, with the phase transition from original hexagonal-close-packed (hcp) structure to γ-Ti2AlC phase structure. With the fluence increasing, more extended defects lead to the symmetry variation and the transformation of a possible δ-phase structure. At the highest fluence of 2 × 1016 cm−2, some face-centered-cubic (fcc) structures are formed from the original hcp structures without amorphization, indicating a great tolerance of irradiation-induced amorphization of Ti2AlC. Based on the phase contrast images and EDPs simulation of the microstructures of the transformed structures, a mechanism for the phase transitions of Ti2AlC is proposed.

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