| The interactions at high temperatures between contacting dissimilar metals and the nature of the phases formed from such interactions are of importance in a variety of applications. Solid-solid interactions are important in such considerations as fiber-matrix reactions, diffusion bonding, and electromigration in interconnects in electronic devices, while solid-liquid interactions have practical significance in liquid metal infiltration, soldering and brazing, liquid-metal coating, and liquid metal corrosion. Related to the latter are investigations on solidification and the effect of various parameters on the resulting microstructure. One parameter of interest to the present investigation relates to the effect of electric fields.;It was found that the electric field played a dominant role in the dynamics of these reactions and in the concomitant phase formation and microstructure evolution. Due to the difficulty in decoupling the large effect of Joule heating from other current effects, the role of the current is not fully understood. Electromigration is perhaps the best-known electric current effect on conductors. However, the nature of the role of the field in these processes could not be unambiguously determined.;In this research, the electric field effect on two simple systems: solid Ni/liquid Al and solid Cu/Ni, was investigated. In solid Ni/liquid Al case, the current effects on the dissolution kinetics of solid Ni into liquid Al, and on the microstructure of solidified samples were investigated. The current had a marked effect on the dissolution rate constant. Correspondingly, the application of the current decreased the activation energy of dissolution significantly. The direction of the DC current was shown to have an effect on dissolution. The influence of a DC current on the microstructural evolution of phases resulting from the dissolution of solid nickel in pure and Ni-saturated liquid aluminum was investigated.;In solid Cu/Ni case, the effect of a DC current on the interdiffusivity, D˜, was investigated. Interdiffusivities were calculated using the Sauer-Freise-den Broeder (SFB) method and the values calculated in the absence of a current were in agreement with previously published results. The influence of the current on D˜ depended on its direction relative to the two interfaces in the tri-layered Cu-Ni-Cu samples. |
