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Age-hardening Mechanisms in a Commercial Dental Gold Alloy Containing Platinum and Palladium

Department of Dental Materials Science, Nagasaki University School of Dentistry, 7-1 Sakamoto-machi, Nagasaki 852, Japan, Center for High Voltage Electron Microscopy, University of Antwerp (RUCA), Groenenborgerlaan 171, B2020 Antwerp, Belgium

K. Udoh

Department of Dental Materials Science, Nagasaki University School of Dentistry, 7-1 Sakamoto-machi, Nagasaki 852, Japan, Center for High Voltage Electron Microscopy, University of Antwerp (RUCA), Groenenborgerlaan 171, B2020 Antwerp, Belgium

K. Yasuda

Department of Dental Materials Science, Nagasaki University School of Dentistry, 7-1 Sakamoto-machi, Nagasaki 852, Japan, Center for High Voltage Electron Microscopy, University of Antwerp (RUCA), Groenenborgerlaan 171, B2020 Antwerp, Belgium

G. Van Tendello

Department of Dental Materials Science, Nagasaki University School of Dentistry, 7-1 Sakamoto-machi, Nagasaki 852, Japan, Center for High Voltage Electron Microscopy, University of Antwerp (RUCA), Groenenborgerlaan 171, B2020 Antwerp, Belgium

J. Van Landuyt

Department of Dental Materials Science, Nagasaki University School of Dentistry, 7-1 Sakamoto-machi, Nagasaki 852, Japan, Center for High Voltage Electron Microscopy, University of Antwerp (RUCA), Groenenborgerlaan 171, B2020 Antwerp, Belgium

The age-hardening mechanism of a commercial dental gold alloy containing platinum and palladium (in wt.%, 15 Cu, 6 Ag, 5 Pt, 3 Pd, 3 Zn, with the balance as gold) was elucidated by means of electrical resistivity, hardness tests, x-ray and electron diffraction and electron microscopy, as well as high-resolution electron microscopy. The sequence of phase transformations during isothermal aging below the critical temperature, Tc = 825 K, was described as follows: disordered solid solution ₀ (FCC) metastable AuCu I' ordered phase (FCT) metastable ₂ disordered phase (FCC) equilibrium AuCu I ordered phase (FCT) + equilibrium ₂ disordered phase (FCC). The hardening was due to the introduction of coherency strain at the interface between the AuCu I' platelet and the matrix. These ordered platelets had mutually perpendicular c-axes to compensate for the strain introduced by their tetragonality. A loss of coherency at the interface brought about softening of the alloy, i.e., over-aging.

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Journal of Dental Research, Vol. 70, No. 10, 1350-1357 (1991)
DOI: 10.1177/00220345910700100701


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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Tani, T. Articles by Van Landuyt, J. Search for Related Content PubMed PubMed Citation Articles by Tani, T. Articles by Van Landuyt, J. Social Bookmarking                         What's this?