Hardening of Low-Alloyed Gold

The development of strengthened high carat Au alloys for jewellery applications is an interesting but challenging task, with significant potential for further development of new age-hardenable alloys. The paper first presents an overview on the possibilities and limitations to harden 22ct Au by conventional means, i.e. by alloying with conventional base metals (solid solution hardening) and in combination with heat treatment processes (age-hardening). The paper then refers to 22ct up to 24ct Au and reports on the enhancement of the age-hardening effect of the primary base metals by additions of selected secondary elements. It is suggested that the prevailing age-hardening mechanism in these types of alloys consists in precipitation of intermetallic phases formed by the primary and secondary additions.