| Abstract |
| The aim of the present study is to investigate the alpha-case formation mechanism between titanium melts and Al₂O₃mold 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 TiO₂interstitial 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. |
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| Key Words |
| Titanium casting, Investment casting, Metal/mold reaction, Alpha-case |
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