金型鋳造したAl-10%Si-Mg系鋳物の時効硬化特性に及ぼす離型温度の影響

摘要

The aging behaviors of Al-10%Si-Mg system alloys cast by permanent mold were investigated by optical microscopy, scanning electron microscopy and micro-vickers hardness measurement. With increasing Mg content from 0.05% to 0.9%, the peak aged hardness in T5 treatment were increased due to increase number density of precipitation. When demold temperatures were increased from 323K to 773K, the peak aged hardness in T5 condition were increased. This tendency was affected by existence of rod-like precipitations after as-cast state. By the amount decreased in the solubility of Mg in the matrix, the crystallization of Mg-including phases (e.g., π -Al8Si6Mg3Fe and Mg2Si) decreased or disappeared and brought some influence for age hardenability of the alloy castings.