Stable strengthening of 990-gold

The addition of 1wt% titanium to gold was found to substantially harden the precious metal and enhance its wear resistance, which makes it attractive for jewellery applications. The enhanced hardening is due to the formation of fine AU4Ti precipitates under the appropriate thermo-mechanical treatments. It has been shown that another hardening mechanism can be induced in wire having a diameter of less than 100μm, which is stable to heating in air up to 200°C. These observations are consistent with the formation of a network of titanium oxide inclusions up to 100μm below the free surface, which has been reported elsewhere. New results have indicated that thin foil of Au-1Ti, which has been subjected to similar thermo-mechanical processing, exhibits similar properties to those of fine wire of this material. Potential uses for the fine wire and foil are described.