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Titanium carbide particle reinforced titanium composites were prepared by in-situ synthesis reaction between titanium and carbon liquid alloys. The phases constitute and microstructures of titanium composite have been investigated by OM, XRD, SEM and EPMA. Although it was possible to synthesize titanium carbide particle reinforced titanium composites, the morphology of in-situ titanium carbide grows into typically dendritic shape due to the compositional supercooling theory. Using computerized image analysis, the average particle size and aspect ratio of in-situ formed titanium carbide is about 28.1 ㎛ and 1.9, respectively.

Excessive iron in aluminum melt produces needle-shaped beta-AlFeSi intermetallic compounds during solidification. The presence of beta-AlFeSi intermetallic compounds can be harmful in the extrusion process because of the high pressure. As a common process, those compounds change from the needle-shaped to the globular-shaped alpha-AlFeMnSi intermetallic compounds through the addition of manganese to the aluminum melt. Those phases settle down during the solidification process, and then such is cut. Note, however, that the efficiency of iron elimination is very low. Our previous study reported that EMS can help the alpha-AlFeMnSi intermetallic compounds form easier and faster and settle down at the bottom of the aluminum melt through the centrifugal force of EMS. To investigate the effect on the efficiency of iron elimination in aluminum melt scrap, EMS current, holding temperature, and time of melt as well as the ratio of manganese to iron were controlled. As a result of this study, lower holding temperature and longer holding time of aluminum melt make iron elimination in aluminum melt more efficient with induced EMS. The best efficiency of iron elimination in aluminum melt was 65.2%with EMS induced at 923k for 4 minutes.

The objective of this study was to optimize the casting design of gamma titanium aluminde automotive turbocharger rotor by means of the practical experiment and numerical simulation. Gamma titanium aluminide rotors were produced by centrifugal casting methods on a laboratory scale. Based on the metal-mold reaction of gamma titanium aluminide, the investment molds were manufactured by an electro-fused Al2O3 mold. The experimental results showed that the castings failed to reach the end of the cavities due to insufficient centrifugal force and a lower fluidity compared to the other metals. Although the satisfactory results were not obtained in the numerical simulation, it was concluded that numerical simulation aided to achieve understanding of the casting process and defect formation in gamma titanium aluminide turbocharger rotor castings.