黒鉛粒子とAl-Ti合金溶湯との反応によるin-situ TiC粒子強化アルミニウム複合材料

抄録

An attempt was made to fabricate in-situ TiC particulate reinforced aluminum composites (TiCp/Al) utilizing the reaction between graphite particles and liquid Al-Ti alloy. Induction furnace equipped with a stirrer was used in order to make it possible to fabricate composites with a high TiC particle volume fraction. TiC particle formation was observed above 1300°C. The size of TiC particles dispersed in the composites was 0.2∼4 μm and increased with the processing temperature. 10 and 20 vol%TiCp/Al with uniform particle dispersion were successfully fabricated, by suppressing of formation of Al₃Ti and Al₄C₃ and stirring of the melt. TiC particle formation behavior around the interface between graphite and liquid Al-Ti alloy was studied by FE-SEM observation and Auger electron spectroscopy analysis. At an early stage of reaction, 0.2∼0.5 μm TiC particles formed on the surface of graphite and then dispersed into the melt. At a late stage of reaction, the Al₄C₃ phase with about 1 μm formed on the surface of graphite. The Al₄C₃ phase decomposed to form TiC particles at about 1 μm distances from the graphite surface. Such a TiC formation behavior was discussed from the thermodynamical viewpoint considering the activity of Ti in the liquid Al-Ti alloy. Young’s modulus and tensile strength of TiCp/Al increased proportionally with the TiC particle volume fraction. The Young’s modulus of 20 vol%TiCp/Al was so high as 104 GPa, being equivalent to that of 20 vol%SiCp/Al fabricated with a powder metallurgical process.