Study Of Interface Reaction And Microstructure Of Investment Casting For Titanium Alloy

Investment casting was adopted for Ti55 alloy in this paper, the effect of different refractory materials and binders to the Interface reaction were studied by using the analysis methods of OM, SEM, XRD and XPS.The research results showed that the thickness of interface reaction layer did not have a obviously different with the two kinds of Y2O3 refractory, it was 10 microns when the foreign production of Y2O3 was adopted, and it was 12 microns with the domestic production, it has a little change with the increase of the thickness of the casting. the effct distance of Interface organization was 250 ~ 300 microns to the 10 mm thick casting, it has a little change with the increase of the thickness of the casting. For Zr O2 face coating materials, the thickness of the interfacial reaction layer was about 30 ~ 40 microns, when adopted the foreign production of Zr O2, the interface reaction layer was thicker than the domestic product of Zr O2 for 4 microns. The thickness of Interface reaction layer increasesd with the increasing of the casting.thickness; the effct distance of Interface organization was 400 ~ 500 microns, it increasesd with the increasing of the casting.thickness. By comparing the results of line scan for different binders at the interface, the effect of two kinds of binders impacting on the interface reaction did not have a obviously different, For the Y2O3 face coating materials, when adopted the No.2 zirconium acetate, the interface reaction layer was thinner than the No.1 zirconium acetate for 1 microns. For the Zr O2 face coating materials, when adopted the No.2 zirconium acetate, the interface reaction layer was thinner than the No.1 zirconium acetate for 5 microns.XRD analysis was carried out on the casting surface, the result showed that the main phase compositions were Ti9O17, Y2O3 and Ti O2 in the casting interface when adopted Y2O3 face coating materials, two kinds of Y2O3 phase compositions showed that the degree of reaction was basically similar, the content of Y2O3 in the casting interface surface adopting the domestic product of Y2O3 was higher than that of foreign production of Y2O3. the main phase compositions were Zr O2、Ti2Oand Ti O2 in the casting interface when adopted Zr O2 face coating materials, two kinds of Zr O2 phase compositions showed that the content of Zr O2 in the casting interface surface adopting the domestic product of Zr O2 was higher than that of foreign production of Zr O2.Making a further XPS analysis showed that at the casting surface of Y2O3 face coating, Y mainly existed in the form of Y2O3, Zr mainly existed in the form of Zr O2; at the casting surface of Zr O2 face coating, Zr mainly existed in the form of Zr O2, Ca mainly existsed in the form of Ca O, and the results analyzed by XPS was consistent with that by XRD.