Effects of Process Parameters on Metal-Mold Reaction of Ti and Ti-6Al-4V Alloy

摘要

The goal of this study is to investigate the effects of process parameters on metal-mold reaction of titanium alloys during investment casting. A plasma arc melting furnace was used for melting and casting of titanium and Ti-6Al-4V alloy. The selection of candidate mold materials is based on the oxide formation of Gibbs free energy data. The metal-mold reaction of titanium castings was determined by means of OM, SEM, EDS, EPMA, XRD and microhardness profiles. The results showed that the titanium castings produced utilizing Al_2O_3 and ZrO_2 mold had apparent reaction layers, whereas a negligible reaction occurred in the castings into graphite, CaO and CaZrO_3 mold. The extent of metal-mold reaction could be reduced significantly with proper choice of binder. Therefore, mold materials and binder process are the most important process parameter of investment casting of titanium alloys.