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 76 as-received and irradiated conditions. The chemistry of very small nanoclus- ters was also investigated. It was found that both theTi/Y and (Ti+Y)/O ratios decrease after radiation, going from 1.22 to 1.09 and from 1.37 to 1.29, respectively. Nanoclusters of sizes greater than 5 nm, were identified by means of STEM Z-contrast imaging, by virtue of their differences in chemical composi- tion with respect to the matrix (the presence ofY andTi in these precipi- tates was confirmed by EDS). It was noted that, in accordance with the results obtained from LEAP analysis for the smallest precipitates, the average size decreased slightly and the number density correspondingly increased going from 7.62±2.0 nm and 2.17 x 1022 m-3 to 8.77±2.1 nm and 2.01 x 1023 m-3 , respectively, in the as-received and irradiated conditions.The very small changes in the sizes of the nanoclusters after radiation generally indicates that the nanoclusters are very stable under irradiation. Defect analysis was also performed on the sample after irradiation.Two beam condition images close to [001], [011], and [111] zone axis were acquired and the dislocation loops identified were quantified.A typical micrograph showing dislocation loops in the neutron irradiated sample is shown in Figure 2.The analysis performed yielded an estimate defect size of 9.1 nm ± 2 nm and a density of 3.3 x 1021 m-3 . Finally, elemental segregation across grain boundaries was performed on a few grain boundaries of the neutron irradiated sample.To reveal the nature of the grain boundary under investiga- tion, t-EBSD maps were collected from the samples under investigation. Figure 3. (a) SEM image of a TEM sample of the neutron irradiated specimen, and (b) image quality map of the same sample as obtained by t-EBSD analysis. This analysis was used to determine grain boundary character distribution of the samples.