1993 Volume 57 Issue 7 Pages 767-773
The formation rate of Ni-Al intermetallic compounds was measured by dipping Ni wire into Al melt in the temperature range between 973 K and 1373 K, in order to determine the kinetic parameters of combustion synthesis of Ni3Al. The Ni wire and Al powders were put into an alumina crucible and vacuum-sealed in a quartz tube. The tube was kept in an electric furnace to cause the compound formation reaction. The microstructure observation and EDX analysis of the dipped Ni wire were performed. It was found that the compound formation reaction occurred at the interface between the molten Al and the Ni wire, and the cylindrical Ni2Al3 layer was formed in the wire. The thickness of the formed layer depended on the holding time and the dipping temperature. The reaction process had been closely similar to the combustion synthesis process of Ni3Al intermetallic compound. Therefore, the kinetic parameters could be determined by the dipping experiment. The experimental data have been analyzed with a cylindrical model which took into account the diffusion process of Al in the compound layer and chemical reaction on the interface between Ni2Al3 and Ni. The diffusion coefficient, DAl, and the reaction rate constant, kc, were estimated as follows.
(This article is not displayable. Please see full text pdf.)
The calculated curves by using present the kinetic parameters were in satisfactory agreement with the experimental values.
