Heavy ion irradiation damage in Zr₃(Al_0.9Si_0.1)C₂ MAX phase

A Zr₃(Al_0.9Si_0.1)C₂ MAX phase-based ceramic with 22 wt.% ZrC and 10 wt.% Zr₅Si₃ has been irradiated with 52 MeV I⁹⁺ ions at room temperature, achieving a maximum dose of 8 displacements per atom (dpa). The response of this MAX phase-rich material to irradiation has been studied using scanning electron microscopy, transmission electron microscopy and X-ray diffraction techniques. Post-irradiation examination of the material revealed a number of crystalline changes to the MAX phase. At low doses, Zr₃(Al_0.9Si_0.1)C₂ maintained a high degree of crystallinity, while at the highest doses, its degree of crystallinity was reduced significantly. A number of radiation-induced phase transformations were observed, including the decomposition of Zr₃(Al_0.9Si_0.1)C₂ into ZrC and other phases, and the formation of β-Zr₃(Al,Si)C₂, a MAX phase with a rearranged stacking sequence. Microstructural examination revealed that the majority of the extended defects in Zr₃(Al_0.9Si_0.1)C₂ lie in the (0001) basal planes. Analysis of X-ray diffraction profiles after heat treating the 8 dpa-irradiated material for 1 h at 300 °C and at 600 °C showed that there were only subtle changes to the profiles relative to that of the 8 dpa-irradiated material which had not been heat treated. Overall, the experimental results of this study show that the Zr₃(Al_0.9Si_0.1)C₂ MAX phase responds less well to irradiation relative to other MAX phases irradiated with high energy heavy ions at room temperature.