Precipitations in a dental Ag-Pd-Cu-Au alloy.

The structure of a dental Ag-PD-Cu-Au alloy has been studied after centrifugal casting and various heat treatments. By transmission electron microscopy, a high density of small fct particles, assumed to be PdCu, was observed, but, in addition, finely-spaced rods of approximately equal to 0.05 micrometer (500 A) diameter with an fcc structure precipitated on the [100] planes of the matrix were found. On the basis of their structure and the pertaining lattice parameter, these rods are assumed to be Cu-rich. They could also be observed by scanning electron microscopy, but not at annealing temperatures lower than 425 degrees C.