[Influence of heat treatment on silver-palladium alloy microstructure]

Cast dental alloys, even those made of precious metals, are not homogeneous. In order to ensure a high-quality cast, it was necessary to determine optimal casting temperature and additional heat treatment to allow for homogenization of the cast in the microarea of the dendritic structure to occur which, in turn, implies chemical inertia of the metal construction to the organic medium of the mouth. A number of melting, homogenizing and aging tests showed the optimal regimen for bringing an Ag-Pd alloy to the level of hardness of the tooth enamel (about 330 HV 0.1) to consist of a technological treatment involving the following procedures: casting at 1100--1150 degrees C, homogenization at 850 degrees C, quenching in water and 20-min precipitation at 350 degrees C.