Structural investigations of the diffusion-zone of soldered dental gold and base metal alloys.

Abstract The aim of this study was to investigate the microstructure of high gold alloy/solder and Co−Cr−Mo alloy/solder interfaces. Wave length dispersive X-ray spectroscopy (WDS) was used to chart elemental distributions across these interfaces. The results strongly suggest that different mechanisms are responsible for forming a joint in different alloy/solder combinations. The couple consisting of a high gold content alloy/gold solder showed no obvious diffusion zone. The couple consisting of the Co−Cr−Mo alloy with a gold wetting agent showed the formation of a new Au-rich Ni-phase along the interface, with diffusion occurring on both sides of the interface. Tensile testing indicated that there was no statistical difference between the strengths of various alloy/solder combinations. Although this finding suggests that all the combinations tested would be clinically acceptable, alloy/solder couples that are characterized by microstructural and compositional heterogeneities may be more susceptible to corrosion in the oral environment.