The molten metal properties and mechanical properties of cast iron are considered to change if the molten cast iron is held in the furnace over an extended period of time for the sintering work or due to line trouble.

  In this study, the chill depth, number of graphite counts, shrinkage cavities, fluidity, and tensile strength of cast iron were investigated when the molten iron was held at 1773K for a long time using a spinel crucible without being carburized. After holding the molten metal for a long time, the graphitization ability was found to decrease, the number of graphite counts decrease, and the chill depth and shrinkage volume increase. The area ratio of pearlite and tensile strength also increased.

  In this study, plaster molds fabricated by three-dimensional (3D) printing were used for the centrifugal casting of pure Al, which is a fundamental centrifugal mixed-powder method. The relationship among processing conditions, relative density and pore structures of centrifugally cast pure Al, and strength of molds were investigated. The relative density and pore structures of Al casts were studied by the Archimedes method and X-ray computer tomography (CT) method. It was found that if the baking temperature of the mold can be increased using a genuine fixing agent and a genuine infiltrant, Al casts having a density equivalent to that of the conventional mold can be produced. Although the strength of the mold can be increased by adding an Al (H₂PO₄)₃ infiltrant, the strength of the mold was also found to decrease when baking was carried out at 600℃. When water was sprayed before baking, the strength of the mold could be improved. However, the part hardened by hydration condensation was found to be limited to the surface region.

  In this study, to obtain knowledge on the phase formation and its stability in Fe₂₀Co₂₀Ni₂₀Cr₂₀B_20-xSi_x high-entropy alloys, the effect of the cooling rate during solidification on the phase formation and the phase change during heating were investigated. Fe₂₀Co₂₀Ni₂₀Cr₂₀B_20-xSi_x alloys were prepared by high-frequency induction melting and the single-roller melt spinning method. The phases formed in each alloy and their phase transformation behavior were investigated by X-ray diffraction (XRD) measurements, scanning electron microscopy with energy-dispersive X-ray spectroscopy, and differential scanning calorimetry (DSC). The results show that the induction-melted alloys were composed of mainly the FCC phase with trace amounts of Cr₂B and Cr₃Ni₅Si₂, and that the amount of Cr₂B decreased and the amount of Cr₃Ni₅Si₂ increased with increasing Si content. In the rapidly solidified alloy prepared at a rate of 7440℃/s, it was found that the FCC phase was mainly formed in the alloy samples with a B content above 12.5 at.%. In contrast, trace amounts of Cr₂B and Cr₃Ni₅Si₂ were formed in addition to the FCC phase in alloy samples with a B content below 10 at.%. The DSC and XRD measurements showed that the alloy solidified at a rate of 7440℃/s exhibited no phase transformation up to 700℃ and remained mostly the FCC phase. In the rapidly solidified alloy prepared at a rate of 2.4 × 10⁵℃/s, it was clarified that the almost amorphous phase was formed in all alloy samples except for that with a B content of 5 at.%. The amorphous phase first transformed into the BCC phase as the temperature rose and then transformed into the FCC phase with a further increase in temperature. The results show that the presented phase transformation behavior roughly corresponds to the results obtained from thermodynamic equilibrium calculations.

  Erosion testing was conducted on iron specimens in various aluminum-based molten binary alloys, and the correspondence between the intermetallic compounds formed at the contact interface and the thermodynamically stable phases was examined. On the basis of the results, the mechanism and dominant factor of the dissolution of the intermetallic layers were investigated. Although the erosion ratio of the specimens by molten Al-3%Mn alloy was significantly small, the ratios by molten alloys of the Al-Si system were great, in comparison to those by other melts. Meanwhile, the intermetallic compounds identified by EBSD corresponded to the stable phases based on the equilibrium calculation of the compositions analyzed by EDS and/or the pseudo binary phase diagrams of the aluminum alloy-Fe systems. In addition, there was a positive correlation between the experimental erosion rate and apparent saturation solubility of Fe to the melts based on the pseudo binary phase diagrams. These results suggest that the dissolution of the layers was caused by almost the same mechanism as the phenomena described by Noyes-Whitney-Nernst equation, and that the saturation solubility of Fe is a dominant factor affecting the diffusion-controlled dissolution from the solid-liquid interfaces under local equilibrium.