等軸共晶粒の生成について

Abstract

To know the origin of equiaxed eutectic grains of eutectic alloys, the macrostructures and microstructures of ingots, solidified under static and vibration conditions, of the zinc-aluminum, aluminum-copper, aluminum-nickel, lead-tin, and tin-zinc systems were examined.In alloys consisting partly of the eutectic, regardless of being a hypoeutectic or hypereutectic alloy, primary crystals separated from the mold wall in the initial stage of solidification and showed the tendency to appear in the central region of the ingots. When primary crystals were not of the leading phase in an alloy, the eutectic which formed on the mold wall grew in to columnar grains independently of the existing primary crystals in the liquid, while when the primary crystals were of the leading phase, the formation of equiaxed eutectic grains occurred on the primary crystals in the liquid.It was also found that eutectic grains on the mold wall could be separated by turbulence in the liquid.