急冷凝固Al-P薄帯の添加による過共晶Al-Si 合金金型鋳物の初晶けい素微細化

抄録

  This purpose of this study was to further enhance refine primary silicon in hypereutectic Al-Si alloys by adding AlP compounds which are heterogeneous nuclei of silicon, instead of adding phosphorus as normally done. The AlP-addition agent was an Al-700ppmP ribbon manufactured by the melt quenching method. The analysis of AlP compounds in normal gravity die castings and ribbon was conducted by SEM-EDS. The results showed the following ; (1) The AlP compounds in the Al-15%Si-70ppmP alloy gravity die castings added with phosphorus as normally done were 2μm in average size. (2) Those in the ribbon were 0.2μm in average size. (3) The number of AlP compounds in the ribbon was significantly large. Next, the refining effects of the ribbon were examined using Al-15%Si-5ppmP and Al-15%Si-15ppmP alloys. The experiments included melting of experimental alloys at 1053K, adding 8.5-17g of ribbon per 1kg of melts at 1023K, holding the melts for 10min to adjust the temperature to 1023K, and casting them into metallic dies using gravity casting. Comparison of normal Al-15%Si-70ppmP alloy gravity die castings and Al-15%Si-16ppmP alloy gravity die castings added with ribbon indicated the following : The average particle size of primary silicon in the former castings and in the latter castings were 14μm and 10μm, respectively. These results confirm that ribbons containing a large amount of fine AlP compounds are more effective as primary silicon refiner than conventional P-addition agents.