NEUTRON-SPECTRUM AND TRANSMUTATION EFFECTS ON THE RADIATION-DAMAGE OFCOPPER-ALLOYS

Experimental results on the neutron spectrum effect on strength and du ctility properties, transmutation rate and change in electric conducti vity of copper-based alloys are presented in the paper. The analysis i s based on the experimental study of radiation damage of pure copper, precipitation-hardened (PH) and dispersion-strengthened (DS) alloys, i rradiated in the mixed spectrum reactor SM-2 and in the fast neutron s pectrum reactor BOR-60 with the doses of (1-16) x 10(21) neutrons cm(- 2). It is shown that accumulation rate of the transmutants (Ni, Zn and He) in the SM-2 reactor is higher than in the BOR-60 reactor, which c an be attributed to a high power flux of thermal neutrons in the SM-2 reactor. This causes a significant reduction in electric resistivity a nd mechanical properties of copper-based alloys. The effect of irradia tion dose and temperature upon DS and PH copper alloy characteristics is analyzed. A threshold softening temperature for PH alloys is shown to be 300 degrees C at a dose of 5 x 10(21) neutrons cm(-2) The mechan ism of the spectrum effect on the shift of the threshold softening tem perature of PH copper alloys is also considered. (C) 1997 Elsevier Sci ence S.A.