Castability of traditional platinum jewelry alloys can suffer if the solidification temperature range is too narrow. An additional challenge is the need to limit the alloy content to maintain the value and noble properties of the jewelry. Thermo-Calc can be used to calculate the non-equilibrium solidification behavior of such alloys and investigate the effect of composition using the included Scheil Solidification Simulation Calculator.
In this example, it is shown that the addition of Co to a Pt-Ru alloy can increase the solidification temperature range leading to improved form-filling during casting. Thermo-Calc can also be used to predict the extent of microsegregation, although in this work, Klotz et al. found no pronounced segregation of platinum for the Pt-1.5Ru3.5Co alloy (recalculated from Klotz, et al., Johnson Matthey Technol. Rev., 2015, 59, (2), 132–14).