Radiation-induced defects and low-temperature hardening in the Fe–Cr alloy

Positron annihilation spectroscopy was used to study processes of accumulation and annealing of vacancy defects in the Fe-15.7 at % Cr alloy of commercial purity and the influence of these processes on the low-temperature hardening of the alloy upon electron irradiation to a damaging dose of 10−3 dpa in a temperature range of 270–370 K. Tensile tests were carried out both in the process of irradiation of the alloy and upon the subsequent annealing. It is shown that at the initial stages of irradiation the increase in the yield stress is caused by the accumulation of vacancy-carbon complexes. With an increase in the radiation dose, the growth of the yield stress is connected with an increase in the density of three-dimensional vacancy clusters. For the alloy irradiated at 370 K, the possibility of the contribution from a high-chromium phase, which is generated as a result of irradiation-accelerated α-α′ phase separation has also been considered.