ボロン添加Al-Mg-Si合金の長時間高温保持による強度変化とMg_2Si析出形態変化

Changes of the strength and the Mg_2Si precipitates in Boron-added Al-Mg-Si alloy, which is attempted to be used as casks in a nuclear power plant, during the long-time duration at the temperatures at 230℃ or 250℃ for 10000hr at maximum. β'-Mg_2Si with rod-like morphology was precipitated after the heat treated. The relationship between the strength and the Larson-Millar parameter (L.M.P.) is represented by liner function when the duration time is longer than 13hr (230℃) or 11hr (250℃); whereas the relationship between the inverse square root of the mean diameter (d^) along long axis of the β'-Mg 2Si precipitates and L.M.P. is also expressed by liner function. The strength change of the B-added alloy is explained using the Ashby's theory concerning precipitation hardening, just similar as that of the Al-Mg-Si alloys without B.