一方向凝固させたAl-17%Si-25ppmP合金鋳塊における初晶Si相の微細化

抄録

  Hypereutectic Al-Si alloy is an industrially important alloy because of its excellent wear resistance. However, since the molten metal temperature of this alloy at the time of casting is high, there are problems such as gas absorption and oxide formation. Therefore, in this study, attempts were made to cast the alloy by reducing the amount of P in the Al-17%Si alloy extremely to as small as 25ppm, together with lowering the molten metal temperature to 720℃. As a result, the primary Si phase was found to be refined. The reason for this can be explained by the solidification sequence of AlP and primary Si phase. In addition, the formation and growth of the primary Si phase, α-Al phase, and eutectic cell are discussed from the viewpoint of constitutional undercooling and heterogeneous nucleation.