Effect of initial microstructure on radiation defect accumulation and annealing in austenitic alloys

The effect of the dislocation structure on the processes of accumulation and annealing of radiation defects in cold-deformed austenitic alloys (Fe-36.5 wt % Ni and Fe-36 wt % Ni-2 wt % Ti) and Cr16Ni15Mo3 steels at the early stages of radiation damage (10-4...1--3 dpa) was studies by positron annihilation.It was found that in deformed samples of steel and alloys with an initial dislocation density of 1...2 centre dot 1011 cm-2 irradiated with 5MeV electrons at room temperature, the concentration of vacancy clusters lowers several times as compared to the samples preliminarily quenched for solid solution. Titanium atoms in the solid solution in the Fe-36 wt % Ni-2 wt % Ti alloy facilitated accumulation of vacancy clusters irrespective of the initial microstructure. At elevated temperatures of irradiation (573K),the evolution of radiation defects for alloy with titanium were affected by fine Ni3Ti particles distributed both homogeneously and heterogeneously (on dislocations).The developed initial dislocation structure and its local inhomogeneity modified annealing of vacancy clusters as well