Platinum-Based Bulk Metallic Glasses for Jewelry Applications

Precious based bulk metallic glasses (BMG) are interesting materials for jewelry and watch making applications due to their properties such as high as-cast hardness, corrosion resistance, and outstanding surface quality. However, high critical cooling rates are required to achieve amorphous solidification which implies challenges for their manufacturing. Thus, they are cast in metallic molds which strongly limits the geometric complexity of cast parts. The present work focuses on the process development for investment-based casting of Pt-P-Cu based BMGs in order to allow for jewelry casting on an industrial scale. The results of centrifugal and vacuum-die casting applied for two different alloys are presented. One of the alloys contains 74wt% Platinum and shows a high glass forming ability, whereas the other alloy has 85wt% Platinum with a significantly lower glass forming ability. Cast filigree jewelry parts with an outstanding surface quality have been demonstrated.