Investigation of as-cast alloys in the Pt-Cr-Ru system

Platinum-based alloys are being developed which have microstructures that are analogous to the γ/γ′ microstructure of the nickel-based superalloys. These Pt-based superalloys have the potential to substitute Ni-based superalloys for even higher temperature applications. The Pt-Cr-Ru system has been studied experimentally as part of this project. The alloys were studied in the as-cast condition, using scanning electron microscope (SEM) and X-ray diffraction (XRD). A solidification projection and liquidus surface were constructed. The major phases were (Ru), (Pt) and ∼CrPt, with ∼Cr2Ru (D8b), ∼Cr3Ru (A15) and ∼Cr3Pt (A15) being minor in extent. Both the tetragonal (L10) and cubic (A1) forms of ∼CrPt were observed. Two invariant reactions were identified in the Pt-Cr-Ru system.