INTERACTION OF IRON-NICKEL ALLOYS WITH LIQUID ALUMINUM .1. DISSOLUTION KINETICS

The dissolution of Fe-Ni alloys containing 90 to 5 mass % Fe in liquid aluminium at 700-degrees-C was found by the rotating-disc technique t o be non-selective and diffusion controlled. Experimentally determined values of the saturation concentration (solubility), c(S), of iron an d nickel from Fe-Ni alloys in the aluminium melt are presented. A depe ndence of the total iron and nickel concentration, c(total), in the sa turated melt upon the iron content C(Fe), in initial Fe-Ni alloys coul d well be described by the linear equations: c(total) = 7.51-0.054 C(F e) at 90% < C(Fe) < 28 % and c(total) = 11.0-0.19 C(Fe) at 28% < C(Fe) < 5%. Considerable deviations of the concentration-time relationships from the Nernst-Shchukarev equation were revealed. The value of the d issolution rate constant was found to decrease by about 20 to 30% in t he 0 to c(S)/2 iron or nickel concentration range. Accordingly, the de crease in value of the iron and nickel diffusion coefficient from an F e-Ni alloy into liquid aluminium was 25 to 40%. For a 90% Fe-10% Ni al loy the value of the diffusion coefficient tends, with increasing iron and nickel concentration in the melt, to the value of the diffusion c oefficient of pure iron in liquid aluminium. For other Fe-Ni alloys in vestigated, these values are less than or close to the diffusion coeff icient of pure nickel in liquid aluminium.