Effect of Indium on the Microstructures and Mechanical Properties of Dental Gold Alloys

摘要

The effect of indium on the microstructures and mechanical properties of a Au-Pt-Cu alloy was investigated. The Au-Pt-Cu-xIn alloys heat-treated at 550°C for 30 min revealed a maximum hardness value of 207 Hv, irrespective of the heat temperature and In contents. Also, the hardness of the Au-Pt-Cu-xIn alloys (x = 0.5, 1.0, 1.5, 2.0) aged at 550°C rapidly increased with increasing aging time, and it reached an almost constant value after 30 min. The hardness of the Au-Pt-Cu-xIn alloys aged at 550°C for 30 min increased with increasing In content until 1.5wt%, but it slightly decreased with more increasing In content. Also, a variation of the tensile strength of the alloys with In contents showed a similar trend of hardness change with In contents. Analysis of EDS and TEM revealed that the microstructure of Au-Pt-Cu-xIn alloys is composed of solid solution with fcc structure and intermetallic InPt_3 precipitate with L1_2 structure. Based on this investigation, it can be concluded that an increase in hardness of Au-Pt-Cu-xIn alloys is ascribed to a complex effect of the precipitation hardening of InPt_3 and the grain size refinement.