Nuclear Science User Facilities 58 Figure 4. a) Cr-Si-P- solute clusters formed by segregation to small loops in the UCSB-1 irradiated Fe-15Cr alloy; b) a proxigram showing the corresponding enrichment of Cr and other solutes to the segregated loop; c) the α and α’ solvus boundaries showing good agreement with a revised Fe-Cr phase diagram for sufficiently large precipitates, with sizes represented by the radius of the circles; d) APT reconstructions showing coarsening of α’ precipitates at 773 K and dissolution at 873 K. a) c) b) d)