A Study on the Identification of Metal/Mold Reaction Product of Ti Investment Casting

摘要

The aim of the present study is to investigate the alpha-case formation mechanism between titanium melts and Al_2O_3 mold during investment casting of titanium alloys. The metal/mold reaction products of titanium castings were investigated by optical microscope, microhardness profile, EPMA and XRD analysis. In this study, the mechanism of alpha-case formation was verified with thermodynamic calculations. The reaction of only Rio_2 interstitial alpha-case formation could not occur spontaneously, on the basis of thermodynamic calculations. From the results of the experimental and thermodynamic calculations, the alpha-case is the reaction products of interstitial oxygen and the substitutional atoms dissolved from the mold materials with titanium, and then this reaction is spontaneous process.