Saturation of ion irradiation effects in Cr2AlC

TL;DR

This study investigates how Cr2AlC MAX phase materials respond to ion irradiation, revealing a structural transition, defect saturation, and stability up to high doses, which explains their resistance to amorphization.

Contribution

It demonstrates the saturation of irradiation effects in Cr2AlC and links this to defect formation mechanisms, advancing understanding of MAX phase radiation resistance.

Findings

Structural transition with increased c and decreased a lattice parameters after irradiation.

Saturation of irradiation effects observed at doses above 1 dpa.

Irradiation-induced antisite defects and C interstitials are key to resistance.

Abstract

Cr2AlC materials were irradiated with 7 MeV Xe26+ ions and 500 keV He2+ ions at room temperature. A structural transition with an increased c lattice parameter and a decreased a lattice parameter occurs after irradiation to doses above 1 dpa. Nevertheless, the modified structure is stable up to the dose of 5.2 dpa without obvious lattice disorder. The three samples irradiated to doses above 1 dpa have comparable lattice parameters and hardness values, suggesting a saturation of irradiation effects in Cr2AlC. The structural transition and irradiation effects saturation are ascribed to irradiation-induced antisite defects (CrAl and AlCr) and C interstitials, which is supported by the calculations of the formation energies of various defects in Cr2AlC. The irradiation-induced antisite defects and C interstitials may be critical to understand the excellent resistance to irradiation-induced amorphization of MAX phases.