Journal of Dental Research, Vol 63, 149-154, Copyright © 1984 by International & American Associations for Dental Research Online Journals
The structure of a commercial dental Ag-Pd-Cu-Au casting alloy
L. Niemi and H. Hero
The structure of a commercial dental Ag-Pd-Cu-Au casting alloy has been
studied by microprobe and X-ray diffraction analyses after various heat
treatments. The composition of phases in equilibrium was established. After
being annealed at 400 degrees C, 500 degrees C, and 600 degrees C for seven
wk, the alloy consisted of three phases: a Cu- and Pd-rich fee phase (alpha
1) with alpha = 0.372nm, a Ag-rich matrix (alpha 2) with alpha = 0.399nm,
and an ordered CsCl-type bcc PdCu phase with alpha = 0.296nm. The PdCu
phase was not observed above 600 degrees C, and the proportion of the alpha
1 phase decreased sharply above 700 degrees C. After being annealed at 900
degrees C, the alloy matrix was partly decomposed at the Cu-enriched grain
boundaries. The decomposed areas grew into the grain interior during
subsequent precipitation hardening. No segregation of Au was detected after
casting, and the element was evenly distributed throughout the alloy
structure after all heat treatments.
