EFFECT OF INDIUM ADDITION ON MICROSTRUCTURE AND STRENGTH OF Au–Pt–Cu–Sn DENTAL BIOMATERIAL

Abstract

Through our previous screening experiments for a new dental alloy design, an Au–11.9Pt–0.6Cu–0.5Sn alloy was selected as a candidate in terms of good strength and surface properties. In this report, the effects of In (indium) on the microstructures and hardness of a dental Au–11.9Pt–0.6Cu–0.5Sn– x In alloy (where x = 0, 0.25, 0.5, 0.75, and 1.0 wt.%) was investigated. The hardness of the Au–11.9Pt–0.6Cu–0.5Sn– x In alloys increased with increasing In content up to 0.75 wt.% and then started to decrease with further increase in In content. Particularly, the alloy containing 0.75% In exhibited noticeably high hardness of 172 Hv. With the addition of In to the Au–Pt–Cu–Sn alloy, grain size decreased and a large number of fine precipitates were formed. The precipitates were identified as Pt 3( Sn, In ) by convergent beam electron diffraction (CBED) and nanospot energy dispersive spectroscopy (EDS). The increased hardness with the addition of In was attributed to the precipitation hardening of Pt 3( Sn, In ) and the grain refinement.