For the purpose of the prediction of casting structures, the heterogeneous nucleation rate in the undercooled melt of solidifying Al-Si alloys was evaluated by comparing experimentally observed macrostructures of solidified ingots with numerically simulated ones. Molten alloys were unidirectionally solidified in an adiabatic mold from a steel chill block located at the bottom of the mold. The top of the mold was heated with an electric furnace to prevent the alloys from nucleation at the melt surface. In the experiment, columnar to equiaxed transition and subsequent equaxed to columnar transition (CECT) were observed. Numerical simulation for the macrostructure formation of the sample ingots was carried out using a cellular automaton (CA) method, and heterogeneous nucleation rate in the solidifying alloys was evaluated by producing structures similar to experimental ones. The heterogeneous nucleation rate was expressed as a probabilistic function with an exponential form of undercooling that determines the probability of nucleation event in simulation, and the value of the exponent was regarded as a heterogeneous nucleation parameter. The heterogeneous nucleation parameter of Al-Si alloy increased with increase in initial solute content of the alloy. An attempt was made to predict the macrostructure of conventional cast ingot using the evaluated heterogeneous nucleation parameter and the simulation predicted macrostructures composed of columnar and equiaxed crystals similar to experimentally observed ones.

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  Melts of spheroidal graphite cast iron were poured into a phenol sand mold at various carbon content in order to investigate the cooling curves, graphite structure and internal shrinkage volume. The surface of each casting was analyzed by EDS.
  The results show that the nodule count increases as the carbon content is raised until the hypereutectic range is entered, after which no further increase occurs. With hypereutectic compositions, the total graphite amount increases but owing to carbon flotation, the increase is concentrated in the upper section of the casting; the middle and lower sections of the casting contain the same graphite amount as with a eutectic composition. The internal shrinkage cavity decreases to zero as carbon content is increased to a eutectic composition and then increases when the hypereutectic composition range is entered. The internal shrinkage cavity is dendritic in the hypoeutectic range but has a smooth shape in the hypereutectic range. Mushy degree of eutectic solidification increases consistently as the carbon content is raised.

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  Laser beam lithography is widely applied to trial production. Resin patterns are inferior to those of metals in heat resistant and mechanical properties. Therefore, if resin patterns can be quickly copied to metal castings, application of the process is expected to remarkably widen.
  After the resin pattern was set in a plaster mold and heated up to the temperature the resin completely burnt out, molten metal was cast in the mold. As a result, in case of thick patterns, cracks generated in the plaster mold. On the other hand, thin patterns could be copied to the metal castings. Cracks ware generated in the mold, sirice the coefficient of thermal expansion was higher than that of plaster, and gas pressure was increased by burning. The effects of the heating rate on mold cracks were also investigated. At low heating rates of the mold, gas pressure decreased preventing the mold from cracking, and resin patterns could be copied to metal castings. Developemnt of new photopolymers for burning patterns in the mold is required for further development of the process.

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  Cast iron with surface pores was made by decarburizing flake graphite cast iron with 4 mass%C and 3 mass%Si at 1123 K in air. The pores were then pressure infiltrated by molten metals such as pure aluminum, AI-12mass%Si alloy or pure zinc at about 100 K higher than liquidus temperature of each metal. The thermal conductivities of pored iron and infiltrated irons were measured.
  The thermal conductivity value decreased greatly from that of untreated flake graphite cast iron with decarburizing. The thermal conductivities of perfectly metal infiltrated irons were calculated. Pure aluminum infiltration decreased the value, but Al-Si alloy or zinc infiltration decreased thermal conductivity compared with untreated flake graphite cast iron. However, experimentally Al infiltrated irons did not exceed the value of untreated cast iron, because of remaining pores by imperfect filling.
  These results clarify problems of thermal conductivity control of cast irons with the decarburizing and /or pressure infiltration technique.

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  A new simulation model for the evolution of macrostructures for Al-base multi-component alloys during solidification has been developed. In this model, the cellular automaton method was coupled with the phase-field method (PF-CA model). The growth kinetics of a dendrite tip for a multi-component alloy was evaluated by phase-field calculations. The obtained growth kinetics of a dendrite tip was applied to the cellular automaton model instead of the commonly used KGT model. In the heat transfer calculation for multi-component alloys, the enthalpy method was used to include alloy properties such as the value of latent heat per unit mass, liquidus and solidus temperature etc. The developed model was used for the simulation of the evolution of macrostructures for Al-base multi-component commercial alloys. The simulation could produce macrostructures similar to experimentally observed macrostructures.

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