Ａｌ‐８％Ｐｂ‐４％Ｓｉ合金の凝固組織と重力偏析

Abstract

Water spray cooled stationary mold casting, water spray cooled movable mold casting and water cooled copper mold casting were tentatively applied to achieve homogeneous dispersion of Pb phase in an Al-8%Pb-4%Si alloy. Casting the alloy into a spray cooled stationary mold 10mm in height and 35mm in diameter at 900°C just above the L1+L2 separating temperature and cooling at a rate 15°C/s result in homogeneous distribution of Si and irregular shaped Pb phases up to 20μm in size. Casting into a water cooled copper mold 80mm in length, 15mm in width and above 8mm in thickness at 850°C just below the L1+L2 separating temperature and cooling at 100°C/s or less result in homogeneous dispersion of spherical Pb about 20μm in diameter. And casting at 900°C into the water coled coopper mold 5mm and 2mm in thickness and cooling at about 300 and 600°C/s respectively result in homogeneous dispersion of irregular-shaped Pb up to 10μm and spherical Pb about 5μm in size respectively. Gravity segregation of Pb is prevented in these casting processes.