Aging of dispersalloy and its effect on the anodic behavior of its amalgams

Anodic polarization measurements of Dispersalloy amalgam in Ringer's solution have shown that its electrochemical behavior is significantly altered by the aging of the alloy at room temperature. Amalgams fabricated from aged alloy are characterized by polarization profiles associated with the presence of Sn7 Hg (gamma2) and Cu-Sn (Cu/Sn less than 3) whereas polarization profiles of amalgams fabricated from relatively fresh alloys are free of current density peaks associated with both of these phases. This aging effect has been attributed to the room temperature oxidation of Ag-Cu eutectic, a component of Dispersalloy. Such oxidation, it has been hypothesized, hinders amalgamation, impairs the effective role of the Ag-Cu eutectic in eliminating the gamma2- phase, and produces corrosion-prone Cu-Sn intermetallics (Cu/Sn less than 3).