Surface Reconstruction of an Annealing Twinned Ag-8Au-3Pd Alloy Wire Under Current Stressing

The durability against electromigration of an annealing twinned Ag-8Au-3Pd wire is about double that of the conventional grained wire under electrical current stressing of 1.23 × 10 5 A/cm 2 . During electromigration, a particular morphology of surface reconstruction comprising a stepwise structure and hillocks can be observed in this annealing twinned wire. The stepwise structure, which has been correlated to longer electromigration life, is postulated to result from dislocation slips driven by electron wind collisions and thermal diffusion of metallic atoms. The simultaneous processes of primary and secondary slips in crossing directions cause hillocks to form at the intersections of both slips. The results also indicated that the electrical current could enhance the grain growth in both wires but had an insignificant effect on the formation of annealing twins.