Annealing effect of radiation defects on the decomposition in nickel-beryllium alloy

Annealing of radiation-induced defects in Ni+2 wt % Be alloy has been studied after irradiation by dose of 1.4x1019 fast neutron/cm2 at 70 deg C by means of measuring electric conductivity and electron microscopy. Irradiation of the Ni-Be alloy at the third recovery stage does not lead to decomposition of oversaturated solid solution. The decomposition in the irradiated alloy occurs at the fourth recovery stage and starts considerably earlier (by approximately 100 deg C) than in a nonirradiated alloy. A substage (at approximately 340 deg C) of the fourth stage has been found in irradiated nickel, which is attributed to the decomposition of small-sized vacancy-impurity complexes. It is assumed that in the temperature range of 400-450 deg C there is a dissotiation of zones appearing in the process of postirradiation aging. A considerable enhancement of electric resistance of a Ni+2 wt % Be sample aged before irradiation at 550 deg C for 1 h has been noted, which is due to the dissolution of the metastable phase under irradiation