The Effects And Mutual Action Of Alloy Elements And SiC Particulate Surface Condition On The Interface Of SiCp/Al Composites

In the thesis, SiC particulate reinforced Al matrix composites were fabricated by mechanical stirring method. By means of transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), the investigation was conducted on effect of alloy elements; SiC particulate surface condition and fabrication processing on the interface in SiCp/Al composites.The results showed that SiC/Al and SiC/Si interface dominated in SiCp/Al-5~10wt%Si-0.5wt%Mg composites. The interface reaction was one of forming spinel (MgAlaO-j) in those composites. The investigation of the interface in as fabricated and remolten conditions of SiCp/Al-Si composites showed that the spinel could form and grow rapidly. The mechanism of the spinel forming was studied by changing the surface condition of SiC particles.SiC/Al interface dominated at the interface of SiC particle reinforced wrought aluminum alloys (Al-Mg-Si). Interface reactions of formation of spinel and aluminum carbide were observed. The interface reaction of forming aluminum carbide could be suppressed by addition of titanium.In a SiCp/Al-Mg-Si-Pb-Ti composite lead existed mainly at the interface because of the effect of titanium, which could promote wetting between SiC and liquid Al-Pb alloy. Lead disabled the action of titanium in the control of aluminum carbide formation. Mutual actions between alloy elements at the interface in SiC/Al composites were revealed.The closest packing crystal plane of SiC crystal is the lowest energy interface in SiC and molten aluminum. The stage interface provides a low energy interface in a composite. The low energy interface is more stable and has low tendency to form aluminum carbide.Theoretical analyses were conducted for the effect of titanium in the control of aluminum carbide formation by thermodynamic calculations.