Al–Mg–Si系合金の時効硬化挙動に及ぼす均質化処理温度と過剰Siの影響

Influences of homogenizing temperature and excess Si on age-hardening behavior of Al–0.93%Mg2Si alloy were investigated. From size distribution obtained by image analysis of secondary phase particles on SEM micrographs, amount of Mg–Si compound in the excess Si alloy was decreased from that in the as-cast state by homogenization at 823 K for 7.2 ks. The amount of Mg–Si compound after homogenization at 773 K lays between those in the as-cast and 823 K homogenized states. Estimating from the analyzed chemical composition, complete dissolving temperature of Mg and Si of the excess Si alloy is 782 K. Conductivity IACS% was decreased with elevating temperature of homogenization, confirming the decrease in amount of the Mg–Si compound and increase in solute concentration. Though the complete dissolving temperature of Mg and Si is elevated, excess addition of only 0.18%Si brings about a strengthening larger than the previously reported alloy containing 0.47%Cu.