Abstract
This study examined the age-hardening by miscibility limit in a multi-purpose dental gold alloy containing platinum. The hardness increased rapidly in the initial stage of the aging process, reached the maximum value, then decreased continuously with aging time. The significant hardness increase resulted from the heterogeneous precipitation of the Pt-rich β phase from the grain boundary of the Au-rich α1 matrix due to the miscibility limit of Au-Pt system. With increasing aging time, the fine Pt-rich β precipitates covered almost the whole matrix, and by further aging, the precipitates grew coarse. The microstructural coarsening reduced the interface between the Au-rich α1 matrix and the Pt-rich β precipitates, which released the lattice strains between the two phases, resulting in a softening effect. In the later stage of aging process, the Au-containing Pt3In particle-like structure was transformed into the Au-depleted particle-like structure containing relatively large amounts of Cu resulting from the overlapping miscibility limit of both Au-Pt and Ag-Cu systems, which was responsible for the slow decreasing rate in hardness in the later stage of aging.
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Hyo-Joung Seol is assistant professor of Department of Dental Materials at Pusan National University in South Korea, Ph.D. in 2003. Her research focuses on characterization of the agehardening mechanism of dental alloys.
Joo-Hee Park M.Sc. is currently working on research of dental gold alloys in the doctoral course at Pusan National University in South Korea.
Ri-Mo Ku is currently working on research of dental gold alloys in the master course at Pusan National University in South Korea.
Mi-Gyoung Park Ph.D. is currently working on research of dental gold and alternative alloys at Catholic University of Pusan in South Korea.
Yong Hoon Kwon is associate professor of Department of Dental Materials at Pusan National University in South Korea, Ph.D. in 1997.
Hyung-Il Kim is chairman of Department of Dental Materials at Pusan National University in South Korea, Ph.D. in 1989. On the editorial board of Dental Materials Journal (International Journal published by the Japanese Society for Dental Materials and Devices).
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Seol, HJ., Park, JH., Ku, RM. et al. Age-hardening by miscibility limit in a multi-purpose dental gold alloy containing platinum. Gold Bull 43, 42–48 (2010). https://doi.org/10.1007/BF03214965
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DOI: https://doi.org/10.1007/BF03214965