The phase composition of the one-phase intermetallic layer(s) and two-phase reaction zone(s) at the interface between a solid iron-nickel alloy, containing 90, 75, 50, 25, 20, 15 and 10 mass% Fe, and the aluminium melt, saturated with alloy constituents at 700 degrees C, was studied by electron probe microanalysis. The formation of binary (FeAl3, Fe2Al7, NiAl3 and surprisingly NiAl2 rather than Ni2Al3) and ternary (FeNiAl9) intermetallic compounds was observed. All the binaries were found to dissolve considerable amounts of a third element (Ni or Fe) and to have a noticeable range of homogeneity. Dissolution of the Fe-Ni alloy base into pure liquid aluminium resulted in a large decrease (three to five times) of the layer thickness compared to the case of the saturated melt.