Precipitation hardening in a dental low-gold alloy

Abstract

Age-hardening characteristics in a dental low-gold alloy composed of 40.0 wt% Au - 35.0 wt% Ag - 7.9 wt% Pd - 7.0 wt% Cu - 5.0 wt% In - 3.5 wt% Zn - 1.5 wt% Sn, were investigated by means of the hardness test, XRD study, SEM observations and EPMA. The following results were obtained. The age-hardening was characterized by a precipitation of Cu-rich α2 phase in the α phase. The softening that occurred following prolonged ageing was due to the heterogeneous formation of the fine nodular precipitates composed of the Ag-rich α1 phase and the Cu-rich α2 phase at the grain boundaries of the α phase.