A heat-treatable alloy experiences a significant change in physical properties because of a specific method of thermal processing during manufacturing procedures. Platinum alloys generally classified as heat treatable are based on varying additions of tungsten (W), gold (Au), gallium (Ga), indium (In) or copper (cu) according to industry sources. Information on these alloys was derived from studies in the late 1970s and published in the early 1990s along with certain patents regarding their application to tension-setting diamonds. The response to heat treatment usually involves an increase in hardness or resistance to indentation, which affords greater wear resistance in service, and an increase in yield strength that makes the material exhibit superior spring properties. Based on international hallmarking standards requiring a minimum of 95% content for unqualified designation as platinum jewelry, the physical properties manipulation available through alloying additions or combinations of cold working are limited. The simultaneous control of chemistry and thermal processing affords a means of manipulating physical properties over a greater range. After consideration of the metallurgical characteristics and physical properties, issues relating to manufacturing methods will be explored with a goal of highlighting potential applications for these materials.

Author: Greg Normandeau, David Ueno