Interaction of iron-nickel alloys with liquid aluminium

Abstract

The dissolution of Fe-Ni alloys containing 90 to 5 mass % Fe in liquid aluminium at 700‡C was found by the rotating-disc technique to be non-selective and diffusion controlled. Experimentally determined values of the saturation concentration (solubility),C _s, of iron and nickel from Fe-Ni alloys in the aluminium melt are presented. A dependence of the total iron and nickel concentration,C _total, in the saturated melt upon the iron contentC _Fe, in initial Fe-Ni alloys could well be described by the linear equations:C _total = 7.51−0.054C _Fe at 90% <C _Fe < 28% andC _total = 11.0−0.19C _Fe at 28% <C _Fe < 5%. Considerable deviations of the concentration-time relationships from the Nernst-Shchukarev equation were revealed. The value of the dissolution rate constant was found to decrease by about 20 to 30% in the 0 toC _s/2 iron or nickel concentration range. Accordingly, the decrease in value of the iron and nickel diffusion coefficient from an Fe-Ni alloy into liquid aluminium was 25 to 40%. For a 90% Fe-10% Ni alloy the value of the diffusion coefficient tends, with increasing iron and nickel concentration in the melt, to the value of the diffusion coefficient of pure iron in liquid aluminium. For other Fe-Ni alloys investigated, these values are less than or close to the diffusion coefficient of pure nickel in liquid aluminium.