In order to examine eutectic solidification in Al-Si alloy, the role of the purity of Al-Si alloy and the eutectic modification agent, strontium or sodium, on eutectic solidification sequences was investigated by a technique of quenching during eutectic reaction.
  If Al-Si alloy contains more than a few ppm of phosphorous (commercial purity alloys), eutectic cells in Al-Si alloy melt grow on centrally-located polygonal silicon which nucleates on AlP particles. However, nucleation of eutectic cells tends to be difficult within the melt with sodium addition due to low phosphorous content, even though the sample is made of identical commercial purity start materials. In the case of samples containing little phosphorous, eutectic phases tend to nucleate on the mold surface and grow in the opposite direction of the heat flow.
  Addition of strontium or sodium results in the morphology of eutectic silicon, which acts as the leading phase of eutectic coupled growth and promotes transition from plate to fiber (coral) shape with decreased anisotropy. This causes eutectic aluminum to grow according to the crystal orientation of the eutectic silicon in unmodified melt, but grow freely with subgrain formations in modified melt.
  These results reveal that eutectic solidification of Al-Si alloy is controlled by the nucleation frequency of eutectic cells depending on phosphorous content and decrease in the anisotropy of eutectic silicon due to modification.

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  The influence of alloying elements on graphite morphology and cooling curves was studied using Ni-C eutectic alloys. Ninety grams of Ni-C parent alloys, prepared using high purity metals, was melted in an Ar atmosphere at 1500°C and cooled at the rate of 40K/min. Their cooing curves were monitored every 0.1s using a B-type thermocouple located at the center of the samples. The graphite morphologies of the samples were observed using an SEM and optical microscope.
  Experimental results showed that spheroidal graphite formed after the crystallization of chunky graphite. This phenomenon completely differed from that of the Fe-C alloys, in which after the spheroidal formation the chunky graphite crystallizes. These results were confirmed by the cooling curves and microstructure.

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  The die cast process is useful for producing parts with smooth surface, high dimensional precision, and complicated shapes. However, with increasing importance placed on energy-saving in recent years, energy-saving has also become an important theme in the die casting process. During the die casting process, molten metal is injected at high velocity and pressure into a mold die cavity to prevent casting defects such as porosity, cold shut, flow line, etc. For this reason, die casting machines require considerable energy using several hydraulic pressure pumps and accumulators. On the other hand, melting furnaces have poor energy efficiency of about 20% due to large energy loss through radiant heat from the furnace surface and exhaust fumes.
  To promote energy-saving in the die casting process, we developed the “hybrid die casting machine with servo and hydraulic mechanism” to enhance energy efficiency. By using this technology, we have successfully reduced energy consumption to 1/6 of that of our previous die casting process.

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