He+ Ion Irradiation Effects on the Phase Stability and Microstructure of High-Purity Zr3AlC2

High-purity Zr3AlC2 samples (>92 wt%) were synthesized and irradiated at room temperature using 100 keV He+ ions at fluences of 2 × 1016 and 1 × 1017 ions/cm2. As a Zr-based MAX phase, Zr3AlC2 is a promising candidate for accident-tolerant fuel cladding due to its compatibility with Zr alloys and the low neutron absorption cross-section of Zr. Our results show that irradiation induces a decrease in the a-lattice parameter and an increase in the c-lattice parameter, along with the formation of anti-site defects and decomposition into ZrC. Cracks preferentially appear along (1000) planes. These findings suggest that Zr3AlC2 has limited structural stability under low-temperature helium irradiation.