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 110 Accomplishments There are two main goals for this research.The first is to determine whether α’ precipitates have formed within an irradiated 14YWT NFA using APT.The second is to compare the microstructure of the neutron irradi- ated 14YWT NFA with a 14YWT NFA irradiated with Fe ions.The ion irradiated 14YWT NFA has the same peak dose and the same irradiation temperature of 1.7 dpa and 288°C, respectively. Following the proposal approval,APT experiments were successfully conducted at the Center ofAdvanced Energy Studies (CAES) in Idaho, on the neutron 14YWT NFA.APT samples were fabricated on the focused ion beam (FIB).Three datasets were acquired and all three have a low background noise at roughly ten counts across the spectrum.They are also very large by atom probe standards sampling as much as 5.21 x 10-21m3 of theAPT specimens, which equates to around 160 x 106 ions. Due to the complexity of the alloy and the size of the datasets acquired, the APT reconstruction process has been challenging. In particular, magnifica- tion effects induced by the atom probe initially warped the dispersoids so that they look like ellipses. However, it can be reported that all three datasets have now been reconstructed and the dispersoids looks spherical. From theAPT data acquired, the neutron irradiated 14YWT NFA appear to not have formed any α’ precipitates. Statistical analysis of the Cr ion maps shows a random distribution of Cr. Moreover, no other precipitate or intermetallic, apart from the NFA dispersoids, were found within the matrix. The 14YWT NFA may be suitable for protecting more delicate components within a tokamak blanket at low temperatures and in a neutron irradiation environment. Figure 3. Atom probe tomographic ion map of neutron irradiated 14YWT NFA (dataset R33_4724). Shown here are C, W, and Si ion maps. As can be seen, there is segregation of these solutes to the grain boundary captured in this dataset.