THE EFFECT OF ANTIMONY ON THE INTERFACES OF CAST ALSI-SIC COMPOSITES

When the matrix alloy of an AlSi7Mg-SiC composite has been modified with antimony, the wetting properties of the System deteriorate. Using transmission electron microscopy and microanalysis it was found that this is probably related to the formation of a film-like amorphous antimony-rich oxide at the matrix-silicon carbide interfaces. Associated with this compound are pores at the interfaces. The film-like compound is generally intermixed with magnesium-aluminium spinel crystallites at the interfaces and with the neighbouring matrix. No antimony-rich phase is found away from the interfaces.