Improvement of Mechanical Properties on Sterling Silver by Al-Sc Master Alloy Addition and Age Hardening Process

Abstract

The purpose of this work is to study the improvement of mechanical properties on sterling silver byaluminium-scandium master alloy addition coupled with age hardening process. The ingots of 93Ag-6Cu-1(Al-2Sc) alloy were prepared from pure elements of Ag, Cu and master alloy of Al-2Sc. Microstructureand microhardness of ingots were investigated. After that ingots were cold-rolled with 80% deformation,subsequently; age hardening process was performed by solution treatment at the temperature of 760 ˚C andaging at the temperatures of 250-350 ˚C. Microstructure, microhardness and tensile property of agedsamples were studied. The result showed that the as-cast microstructure was dendrite which consisted ofAg-rich phase and the Cu-rich phase presented at the interdendritic dendrite with the averaged hardness of80 ± 5 HV. The microstructure of aged samples showed equiaxed grains together with twin lines. Thehardness of aged samples depended on the aging temperatures. It could be concluded that the averagedhardness was maximum by aging at 300 ˚C for 60 minutes, showed 180 ± 5 HV. The averaged maximumtensile strength and yield strength exhibited 565 ± 5 and 517 ± 5 MPa, respectively.

Keywords : Sterling Silver / Alloying Element / Age Hardening / Aluminium Scandium MasterAlloy