INFLUENCE OF NEUTRON IRRADIATION AND AGEING ON BEHAVIOR OF SAV-1 REACTOR ALLOY

Abstract

This study observed the effect of neutron irradiation and ageing on the microstructure, hardness, and corrosion resistance of SAV-1 (Al–Mg–Si) alloy. The investigated material was irradiated with neutrons to fluences of 1021–1026 n/m2 in the WWR-K research reactor and kept in dry storage. Long-term irradiation led to an increase in hardness of the alloy and a deterioration of pitting corrosion resistance. Post-irradiation ageing for 1 h at 100–300 °C resulted in a decrease in microhardness of the irradiated SAV-1. The effect of post-irradiation ageing on pitting corrosion was made clear through the formation of Guinier-Preston zones and secondary precipitates in the Al matrix. Ageing at 250 °C corresponded to the development of stable microstructure and the highest corrosion resistance for the irradiated samples. Mg2Si, Si, and needle-shaped β″ precipitates were formed in SAV-1 alloy that was irradiated with low fluences. β″ and clusters of rod-shaped B-type precipitates were observed in highly irradiated samples. The precipitates were similar to those seen in non-irradiated pseudo-binary Al–Mg2Si alloys with Si excess.