On the Corrosion Resistance of Titanium Alloys (2nd Report). The Equilibrium Diagram of the Titanium-Platinum System

Abstract

The equilibrium diagram of the titanium-platinum system has been investigated in the whole range of the composition by metallographic examination, X-ray analysis, measurement of melting point, and differential thermal analysis. The diagram obtained from the experimental results is shown in Fig. 4. Three intermediate compounds (Ti₃Pt), (TiPt), and (TiPt₃) were found to exist. Among them the crystal structure of Ti₃Pt is of β-walfram type, and TiPt₃ is of face center cubic. An eutectic reaction\ ightleftarrowsL_β+Ti₃Pt occurs at 43% platinum and 1310°, and an eutectic reaction L\ ightleftarrowsTi₃Pt+TiPt₃ at 68% platinum and 1320°, also an eutectic reaction L\ ightleftarrowsTiPt+TiPt₃at 85% platinum and 1780°, and a peritectic reaction L+TiPt₃\ ightleftarrowsγ (Pt) at approximately 95%platinum. An eutectoid reaction β\ ightleftarrowsα+Ti₃Pt occurs at 12% platinum and 840°. The solubility of platinum in beta titanum is approximetely 30% at the eutectic temperature and 10% at 1000°, and the solubility of platinum in alpha titanium is 2% at the eutectoid temperature.