Microstructural Examination of Pure Copper and Three Copper Alloys Irradiated in FFTf

摘要

This paper examines the microstructure of the high purity copper and three commercial alloys whose macroscopic properties were least influenced by the fast reactor irradiation. While pure copper evolved in a manner consistent with the behavior of other pure metals, the dispersion-hardened Al-25 alloy appeared to be essentially unaffected by radiation. The Al sub 2 O sub 3 dispersoids are not changed by radiation and the matrix shows no evidence of void or bubble formation and very little evidence of dislocation evolution. The solution-strengthened alloy MZC also showed no evidence of void formation but exhibited several types of precipitation, which may account for the 1% increase in density that was measured after irradiation. In the precipitation-strengthened alloy CuBeNi voids formed in those regions (approx.75%) which had recrystallized and not in those regions resisting recrystallization. The recrystallized regions also contained large precipitates which are rich in beryllium and were often surrounded by void halo's resulting form transmutation of beryllium to helium. In the unrecrystallized regions there was a high density (approx.5 x 10 sup 16 cm sup -3 ) of small (approx.5 mm) precipitates. (ERA citation 11:030097)