Page 1 Page 2 Page 3 Page 4 Page 5 Page 6 Page 7 Page 8 Page 9 Page 10 Page 11 Page 12 Page 13 Page 14 Page 15 Page 16 Page 17 Page 18 Page 19 Page 20 Page 21 Page 22 Page 23 Page 24 Page 25 Page 26 Page 27 Page 28 Page 29 Page 30 Page 31 Page 32 Page 33 Page 34 Page 35 Page 36 Page 37 Page 38 Page 39 Page 40 Page 41 Page 42 Page 43 Page 44 Page 45 Page 46 Page 47 Page 48 Page 49 Page 50 Page 51 Page 52 Page 53 Page 54 Page 55 Page 56 Page 57 Page 58 Page 59 Page 60 Page 61 Page 62 Page 63 Page 64 Page 65 Page 66 Page 67 Page 68 Page 69 Page 70 Page 71 Page 72 Page 73 Page 74 Page 75 Page 76 Page 77 Page 78 Page 79 Page 80 Page 81 Page 82 Page 83 Page 84 Page 85 Page 86 Page 87 Page 88 Page 89 Page 90 Page 91 Page 92 Page 93 Page 94 Page 95 Page 96 Page 97 Page 98 Page 99 Page 100 Page 101 Page 102 Page 103 Page 104 Page 105 Page 106 Page 107 Page 108 Page 109 Page 110 Page 111 Page 112 Page 113 Page 114 Page 115 Page 116 Page 117 Page 118 Page 119 Page 120 Page 121 Page 122 Page 123 Page 124Nuclear Science User Facilities 54 Further, at 63(25) nm and 4 x 1019 loops/m3 , the largest loops inTi3SiC2 were observed after irradiation to 9 dpa at 1000°C (Figure 2). However, these were only observed near stacking faults, and the majority of grains imaged showed no signs of irradia- tion damage in the bulk (Figure 2d). At 70(25) nm, the dislocations loops inTi3AlC2 after irradiation to 9 dpa at 500°C were larger, and more numerous with a density of 8 x 1020 loops/ m3 (Figure 3). Basal perturbations were also observed inTi3AlC2 at these conditions (Figure 3d).TiC impurity particles were significantly more susceptible to irradiation damage, forming extensive defect clusters and dislocation loop networks (Figure 4). Even more notable is the appearance of a large defect-free denuded zone, nearing 1 μm in size, inTi3SiC2 irradi- ated to 9 dpa at 500°C (Figure 1c). Furthermore, at 1000°C, most grains on the order of 3–5 μm appear to be free of damage altogether (Figure 2d). This finding unequivocally demon- strates the ease of mobility of defects along the basal planes, and the lack thereof in the impurity particles. These results confirm our initial conjecture that we postulated when we started this work. Namely, the A-layer in the MAX phases, sandwiched between hard M3 X 2 blocks, would provide stable defect accommoda- tion sites, allowing for point defect accumulation, migration, and their ultimate annihilation.With increased irradiation temperature, the ease of migration along the basal planes allows for enhanced recovery of irradiation defects, resulting in the formation of coherent dislocation loops or annihila- tion of defects at the grain boundaries. The results from this work show that the MAX phases, notablyTi3SiC2, are able to withstand neutron irradiation damage, and recover from microstruc- tural distortion with high-temperature irradiation.The project has thus provided the foundation for future experimental and theoretical studies for this promising family of materials for nuclear applications. Future Activities This project has concluded. No further work is expect to be performed. Samples will be transferred to the NSUF Sample Library and are available for future proposals.