• Journal of Technologic Dentistry
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• v.25 no.1
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• pp.63-70
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• 2003

The microstructure and hardness of a porcelain fused Au-Pt-Cu-In alloy was investigated using optical microscopy, secondary electron microscopy, electron probe microanalyzer, transmission electron microscope, and vickers hardness. The hardness of the heat-treated Au-Pt-Cu-In quartenary alloy reached a maximum value in 30 min at 550$^{\circ}C$ in the range of 150 to 950$^{\circ}C$. In the aged Au-Pt-Cu-0.5In alloy at 550$^{\circ}C$, the hardness of the alloy rapidly increased until 30min with increasing aging time and after that it was remained nearly constant value. Based on above results, glazing and final aging of the porcelain fused Au-Pt-Cu-0.5In alloy were performed at 920 and 550$^{\circ}C$, respectively. The hardness of Au-Pt-Cu-0.5In alloy glazed at 920$^{\circ}C$ was 90 Hv and that of the alloy aged for 30 min at 550$^{\circ}C$ increased to 160 Hv. This indicates that a ceramic-metal crown with high strength can be manufactured using the glazing at 920$^{\circ}C$ and followed final aging at 550$^{\circ}C$ for 30 min.

• Journal of Biomedical Engineering Research
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• v.24 no.3
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• pp.203-208
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• 2003

The effect of indium on the microstructure and hardness of a Au-Pt-Cu ternary alloy was investigated using optical microscopy, differential scanning calorimeter, scanning electron microscopy x-ray diffractometry, electron probe microanalizer and vickers hardness tester. A hardness of the solution floated Au-Pt-Cu-0.5In quarternary alloy with 0.5 wt.% was reached a maximum value (162 Hv) in 30 min at 550$^{\circ}C$ in the range of 150 to 950$^{\circ}C$ but that of the alloy was rapidly increased until 30 min with increasing aging time at 550$^{\circ}C$ and after that was remained almost constant value. Also, the microhardness of the matrix Au-Pt-Cu ternary alloy aged at 550$^{\circ}C$ for 30 min was continuously increased with indium contents and the grain size of Au-Pt-Cu ternary alloy decreased as increased indium contents. Analyses of EPMA and XRD revealed that the matrix Au-Pt-Cu-In quarternary alloy is composed of fcc structure and intermetallic InPt$_3$ precipitate with Ll$_2$ structure. Based on this investigation, it can be concluded that an increase in microhardness of Au-Pt-Cu-In quarternary alloy is due to precipitation hardening InPt$_3$ and grain size refinement.