18 carat yellow gold alloys with increased hardness

An investigation was carried out by Mintek to examine the influence of a range of alloying additions (titanium, vanadium, chromium, molybdenum, cobalt, zirconium, boron, aluminium, silicon, zinc, platinum, palladium, rhodium, iridium and ruthenium) on the formability, hardenability and colour of 18 carat gold alloys. This paper provides chemical formulae for yellow 18 carat gold alloys that have hardnesses which are higher than the hardnesses of the corresponding conventional 18 carat alloys, in particular in excess of 300 HV, but with colours similar to conventional 18 carat gold. A preparation method for the alloys will also be described, which includes the steps of melting, annealing, quenching, cold working and age hardening.