An atomic resolution study of radiation-induced precipitation and solute segregation effects in a neutron-irradiated W-25 at.% Re alloy

摘要: Abstract The phenomena of radiation-induced precipitation and solute segregation effects in a W-25 at.% Re alloy have been investigated using the atom-probe field-ion microscope. This is supersaturated with respect to solvus line primary β-solid solution. specimens had irradiated Experimental Breeder Reactor (EBR-II) fast neutron fluence ~4 × 1022 neutrons cm−2 (E > 0.1 MeV) at 575, 625 675°C. corresponds 8.6 dpa an average displacement rate, for 2 year irradiation time, 1.4 10−7 s−1. results present work show significant alteration microstructure this as result irradiation. Coherent, semicoherent incoherent precipitates composition ~Wre3 were detected; precipitate's number density ~ 1017 cm−3 mean diameter ~40A. coherent WRe3, not associated either or planar defects any impurity atoms. Therefore, true homogeneous occurs alloy. WRe3 4He atoms; i.e. these may heterogeneously nucleated. Voids ~1017cm−3 ~90A detected. Neither enrichment enhancement was found voids. A two-dimensional phase has observed grain boundary. physical argument presented nucleation vicinity cascades. It suggested that first step formation tightly-bound mobile mixed dumbbells which react form immobile di-rhenium cluster. possible sequence point-defect reactions detailed can lead growth cluster into precipitate most likely driven by irreversible vacancy: self-interstitial atom (SIA) annihilation reaction, recently Cauvin Martin. Point defect mechanisms all other observations are also discussed.