Abstract The microstructure of metal matrix composites of AA2024, AA 6061 and EN AC 44300 alloys with 10 vol. % Saffil fibers were investigated using transmission electron microscopy. The fibers in the preform were stabilized using liquid glass binder and fired at 800oC resulting in formation of amorphous silicon oxide joints. The preforms infiltration with AA2024 leads to reaction of liquid metal with SiO2 binder substituting it with fine-crystalline mixture of MgO, ??Al2Cu and silicon. Similar operation with AA6061 leads to binder substitution with porous ?amorphous Al2O3 and MgO. Only squeeze casting of EN AC 44200 with Mg<0.6 % left most of the binder unchanged and allowed to obtain practically clean Saffil/ matrix interfaces.