[Effects of au content on ageing characteristics of dental Ag-Pd-Cu-Au alloys (II). Change in ageing characteristics by different solution treatment temperature (author's transl)].

Abstract

Commercial Ag-Pd-Cu-Au alloys of which Au content was changed from 0 to 30 wt. % were quenched from 800 degrees C designated by JIS as solution treatment temperature. The structure of the alloys were composed by f. c. c. alpha 2 phase and L20 type ordered phase (beta phase). When solution treatment temperature was elevated up to 940 degrees C-980 degrees C, as quenched structure shows only one phase named alpha phase. A new hardening stage which was not appeared in the case solution treated at 800 degrees C was found at the temperature near 250 degree C in age-hardening curve, and the maximum hardness given by ageing increased. The maximum hardness given by ageing of the alloys which were solution treated at 940 degrees-980 degrees C was not caused by precipitates appeared at grain boundary but by precipitates in the grain.