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

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