1 Search Results

Here, we report on the characterization of defects formed in polycrystalline Ti₃SiC₂ and Ti₂AlC samples exposed to neutron irradiation – up to 0.1 displacements per atom (dpa) at 350 ± 40 °C or 695 ± 25 °C, and up to 0.4 dpa at 350 ± 40 °C. Black spots are observed in both Ti₃SiC₂ and Ti₂AlC after irradiation to both 0.1 and 0.4 dpa at 350 °C. After irradiation to 0.1 dpa at 695 °C, small basal dislocation loops, with a Burgers vector of b = 1/2 [0001] are observed in both materials. At 9 ± 3 and 10 ±more » 5 nm, the loop diameters in the Ti₃SiC₂ and Ti₂AlC samples, respectively, were comparable. At 1 × 10²³ loops/m³, the dislocation loop density in Ti₂AlC was ≈1.5 orders of magnitude greater than in Ti₃SiC₂, at 3 x 10²¹ loops/m3. After irradiation at 350 °C, extensive microcracking was observed in Ti₂AlC, but not in Ti₃SiC₂. The room temperature electrical resistivities increased as a function of neutron dose for all samples tested, and appear to saturate in the case of Ti₃SiC₂. The MAX phases are unequivocally more neutron radiation tolerant than the impurity phases TiC and Al₂O₃. Based on these results, Ti₃SiC₂ appears to be a more promising MAX phase candidate for high temperature nuclear applications than Ti₂AlC.« less