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 1242015 | ANNUAL REPORT 53 electrical properties of the materials will be characterized during post- irradiation examinations.The results will provide an initial database that can be used to assess the micro- structural responses and mechanical performances of these ternaries. Accomplishments As of FY 2015, this project has been deemed completed.The irradiation of samples ofTi3SiC2 andTi3AlC2 was conducted throughout the first two years of this project, which were then left to cool awaiting characteriza- tion. Due to unavoidable delays within the INL facilities, work on this project was delayed throughout FY 2013. In FY 2014, the receipt, cask unloading, experiment disassembly, and cata- loguing of specimens were successfully accomplished, led by Collin Knight and KarenWright. Upon examination, several samples were found to be fused together, notably in the 100°C capsules at higher irradiation conditions, and were unavailable for characterization. Work continued throughout FY 2014 and into FY 2015 as samples ofTi3SiC2 andTi3AlC2, most desirably those irradiated to 9 dpa, became available for characterization. Samples were mounted in metallo- graphic epoxy to protect the workers from radiation exposure, and were first analyzed using XRD for phase and structure analysis.According to the Rietveld refinement of the XRD patterns collected, bothTi3SiC2 and Ti3AlC2 remained crystalline after irradiation, and both resulted in limited TiC formation.After irradiation at 100°C, a-LPs decreased and the c-LPs increased. Conversely, the lattice param- eters of samples irradiated at all doses at 500 and 1000°C, were close to the pristine values, indicating that dynamic recovery was occurring at temperatures as low as 500°C. With the collaboration of Lingfeng He at INL, extensiveTEM work was conducted to explore the irradiation induced defects inTi3SiC2 andTi3AlC. Dislocation loops with b = 1/2[0001] were observed in samples ofTi3SiC2 irradiated at 500°C, 21(6) nm dia. at 1 dpa, and 30(8) nm at 9 dpa (Figure 1a,b). In theTi3SiC2 samples irradiated to 9 dpa, both at 500 and 1000°C, voids were observed within the grain boundaries (Figure 1d). The MAX phases show great potential for irradiation damage tolerance due to their nanolayered structure. — Darin J.Tallman, Ph.D.Research Assistant