Journal of Dental Research, Vol 75, 1497-1502, Copyright © 1996 by International & American Associations for Dental Research Online Journals
Microstructure and segregation behavior of palladium in silver-copper-palladium alloys
K. I. Chen, J. H. Lin and C. P. Ju
Department of Materials Science and Engineering, National Cheng-Kung University, Tainan, Taiwan, ROC.
It has been reported that the addition of palladium can modify the
microstructure and improve the properties of Ag-Cu eutectic alloy as well
as admixed Cu-rich amalgam. The purpose of this work was to study the
microstructure and segregation behavior of palladium in a series of
Ag-Cu-Pd alloys. All microstructural and microchemical results consistently
indicated a strong tendency for palladium to form the ordered Cu3Pd
superlattice in the copper-rich phase of the present ternary alloys.
Transmission electron microscopic examination indicated that, in addition
to the large Cu-rich particles, numerous small (typically tens of
nanometers) Cu-rich particles were distributed in the Ag-rich phase. In the
alloys containing 10 and 15 wt% Pd, the Cu3Pd superlattice had an
L1(2)-type crystal structure. In the alloy containing 20 wt% Pd, the Cu3Pd
had a periodic (regular) APB structure. The solubility of palladium in the
Cu-rich phase was always much larger than that in the Ag-rich phase. The
ratio of the palladium concentration in the copper-rich phase to that in
the silver-rich phase decreased with the overall palladium content.
