Abstract
A kinetic study has been made on the dissolution process of Cu-44.0Ni, Cu-23.8Ni and Cu-11.9Ni alloys in liquid Bi. The measurements of solution rate were carried out under a static and isothermal condition at 400°, 450° and 500°C.
The results showed that the dissolution process for the Cu- and Ni-components followed approximately a modified Nernst-Brunner’s equation which was introduced by assuming that each component of the alloys has a solution rate constant corresponding to the alloy composition and dissolves homogeneously. It was also deduced that the rates of dissolution would be determined by the diffusion process of dissolved atoms through the boundary layer adjacent to the dissolving surface of the alloy. At each temperature, the values of solution rate constants obtained for the Cu- and Ni-components of the alloys increased with the increase in Ni-contents of the alloys. On the other hand, these values for each alloy increased linealy with the increase in the product of saturation concentrations of Cu and Ni in Bi. It was also found that, independent of temperature and the kind of alloys, there was a linear relationship between the solution rate constants and the ratios of the saturation concentration of Ni to those of Cu in Bi. In addition to this, the measured values of activation energy for dissolution of Cu- and Ni-components were almost equivalent in the alloys.
From these facts, it was assumed that there are the strong mutual interaction between Cu and Ni atoms in dissolution process which promotes a cooperative dissolution of these alloy components.
