Interfacial reactions between Ti and Y ₂ O ₃ /Ca ₄ Ti ₃ O ₁₀ composites

Abstract

Abstract In titanium casting, the interfacial reactions between selected Y 2 O 3 /Ca 4 Ti 3 O 10 composites in contact with titanium at 1600°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 Y 2 O 3 /Ca 4 Ti 3 O 10 composites formed through hot pressing at 1500°C or annealing at 1600°C. These phases were identified as Ca 4 Ti 3 O 10 , Y 2 O 3 , and minor amounts of CaO. The amount of Ca 4 Ti 3 O 10 in the composites gradually decreased as the amount of Y 2 O 3 increased. When the Y 2 O 3 /Ca 4 Ti 3 O 10 composites were in contact with titanium, a reaction layer of α‐Ti and Y 2 O 3 was formed near the interface of the composite side. Large amounts of calcium and oxygen were expelled toward the composite side from Ca 4 Ti 3 O 10 near the interface to form CaO, which precipitated in the Ca 4 Ti 3 O 10 and Y 2 O 3 phases. Furthermore, no reaction phases were detected in titanium. Ca 4 Ti 3 O 10 and Y 2 O 3 can function as diffusion barrier layers to effectively suppress the diffusion of oxygen into titanium.