Interfacial reactions between Ti and Y2O3/Ca4Ti3O10 composites

Abstract

In titanium casting, the interfacial reactions between selected Y2O3/Ca4Ti3O10 composites in contact with titanium at 1600 degrees C for 30 minutes in an argon environment were characterized using X-ray diffraction, scanning electron microscopy, and analytical transmission electron microscopy. Before contact with titanium, reaction phases of the Y2O3/Ca4Ti3O10 composites formed through hot pressing at 1500 degrees C or annealing at 1600 degrees C. These phases were identified as Ca4Ti3O10, Y2O3, and minor amounts of CaO. The amount of Ca4Ti3O10 in the composites gradually decreased as the amount of Y2O3 increased. When the Y2O3/Ca4Ti3O10 composites were in contact with titanium, a reaction layer of alpha-Ti and Y2O3 was formed near the interface of the composite side. Large amounts of calcium and oxygen were expelled toward the composite side from Ca4Ti3O10 near the interface to form CaO, which precipitated in the Ca4Ti3O10 and Y2O3 phases. Furthermore, no reaction phases were detected in titanium. Ca4Ti3O10 and Y2O3 can function as diffusion barrier layers to effectively suppress the diffusion of oxygen into titanium.