한국주조공학회

A noble technique has been developed for fabricating in situ formed TiCp/Al composites. In this process, fairly stable TiC particles were in situ synthesized in liquid aluminum by the interfacial reaction between an Al-Ti melt and SiC, which is a comparatively unstable carbide from the view-point of thermodynamics. It is possible in the present process to generate TiC particles of nearly 1 μм in diameter, even utilizing SiC of 14 μм as raw material. However, the dispersion behavior of TiC particles in the matrix depends on the size of the raw material SiC. Decomposing finer SiC makes the dispersion of TiC particles more uniform and the mechanical properties of composites are improved accordingly. The structure of in situ composites and their mechanical properties are affected by the fabrication temperature and the stirring time. It has been found that the most suitable condition for fabrication should be applied depending on the size of the raw material, even if the same kinds of carbide are used. Furthermore, although Al-Ti-Si system intermetallic compounds are detected in a TiCp/Al-Si composite which is fabricated by conventional melt-stirrng method, these compounds can not be observed in a TiCp/Al-Si composite made by this in situ production method. Hence the mechanical properties of the in situ TiCp/Al-Si composite are superior to those of the conventional TiCp/Al-Si composites.