Tarnish and corrosion behaviour of palladium-silver alloys

Binary and commercial palladium-silver dental alloys show a greatest resistance to both tarnish and corrosion at compositions of between 50 and 75% Ag, most probably due to saturation of the d-electron shell in this composition range. The commercial Pd-Ag alloys have more corrosion resistance, but a lower tarnish resistance than the binary Pd-Ag alloys, due in part to the minor alloying with indium or zinc. The addition of copper increases the segregtion of silver, which adversely affects both tarnish and corrosion resistance. A solutionization heat treatment degrades tarnish resistance, but does not affect corrosion resistance.