Single crystals of MgO•3Al2O3 were irradiated with 1MeV neutrons to fluences of 8.3 x 1022/m2 at 100C or 2.4 x 1024/m2 at 470C. Knoop microhardness testing at several orientations on the (100) plane of both irradiated and non-irradiated crystals was carried out using various indentation loads. The change in the hardness profile of the crystals was almost the same after the 2 irradiation treatments. The hardness increased by between 4 and 15%, due to the irradiation, depending upon the crystallographic orientation. The larger changes were observed for orientations of between <001> and <011>. It was found that, whereas both the {111}<11¯0> and {110}<11¯0> slip systems were simultaneously active in the non-irradiated material, the {110}<11¯0> system appeared to be the predominant slip system in the irradiated crystals. It was concluded that restriction of the {110}<11¯0> slip system was caused by irradiation-induced interstitial ions.

T.Yano, M.Ikari, T.Iseki, E.H.Farnum, F.W.Clinard, T.E.Mitchell: Journal of the American Ceramic Society, 1995, 78[6], 1469-74