| 1224 Microstructures of Ga-added 35Ag-30Pd-20Au-15Cu alloys in relation to their machanical properties | ||
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S.-I. GOTO, P. CHURNJITAPIROM, Y. MIYAGAWA, and H. OGURA, The Nippon Dental University, Niigata, Japan Objectives: It was reported in our previous study that the addition of Ga to 35Ag-30Pd-20Au-15Cu alloy highly improves its strength and this type of alloy has high potential for the application of ul-tra-low fusing ceramics. The strengthening mechanism of this alloy, however, has not been clarified. The purpose of this study was to investigate the microstructures of 35Ag-30Pd-20Au-15Cu alloys containing different amount of Ga as the additive metal, in relation to their mechanical properties. Method: Based on the previous result, a 35%Ag-30%Pd-20%Au-15%Cu alloy was chosen as a mother composition in the present study. Ten 35Ag-30Pd-20Au-15Cu alloys containing different amount of Ga (0%, 0.25%, 0.5%, 0.75%, 1%, 1.25%, 1.5%, 2%, 4% and 6% by mass) were prepared using an induction melting unit in Ar gas atmosphere. A thin square specimen (10x10x1 mm) was prepared using each of the ten experimental alloys, following a dental casting procedure. The micro-structures of these as cast specimens were analyzed using an electron microprobe analyzer, and the phases formed in these alloys were determined. In addition the content of each metal element was measured for different phases formed in the specimen. Results: The original alloy (0% Ga) consisted of Pd-Cu-rich and Ag-Pd-Cu-Au-rich phases, and the similar structure was found at 0.25% Ga. At more than 0.5% Ga, the alloys also consisted of two phases, Ag-Pd-Au-Cu-rich phase which rarely contained Ga and Pd-Cu-rich phase which had the segregation of Ga. In the latter phase, Ga, Pd, and Cu increased with the increase in the Ga content. Conclusion: The microstructure of the Ga-added 35Ag-30Pd-20Au-15Cu alloy changes with the increase in the content of Ga in the range of 0-6 mass%, which suggests that the reported change in the mechanical properties of the Ga-added 35Ag-30Pd-20Au alloy is due to the different microstructures containing different amount of Ga. | ||
| Seq #121 - Casting Alloys I 3:45 PM-5:00 PM, Thursday, 7 March 2002 San Diego Convention Center Exhibit Hall C | ||
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