Enhancing the Self-Healing Efficiency of Ti₃AlC₂ MAX Phase via Irradiation

Self-healing materials are highly desirable in the nuclear industry to ensure nuclear security. Although extensive efforts have been devoted to developing self-healing materials in the past half century, very limited successes have been reported for ceramics or metals. Here, we report an intrinsic self-healing material of Ti₃AlC₂ MAX phase, which exhibits both ceramic and metallic properties, and a strategy for further enhancing the self-healing via irradiation is proposed. Quantitative <i>in situ</i> transmission electron microscopy tensile testing reveals that the fracture strength of 1.58 GPa is achieved on thoroughly fractured Ti₃AlC₂, corresponding to the self-healing efficiency of 19.8%, which is increased to 28.1% after irradiation. <i>In situ</i> irradiation experiments, atomic-resolution characterizations, and molecular dynamics simulations reveal that spontaneous rebonding of partial atoms on fracture surfaces is responsible for the self-healing, and irradiation-enhanced atomic migration, interplanar spacing increment, and gap-filling contribute to the self-healing enhancement.