Interface reaction between SiO2-based ceramic core and yttrium-containing DD5 single crystal superalloy

Abstract Y was added to DD5 superalloy, and the interface reaction between the superalloy and the ceramic core at various positions on the cast turbine blade was studied using scanning electron microscopy, energy spectrum analysis, and other methods. The study aimed to investigate the influence of Y on this reaction. Results show that superalloys containing yttrium exhibit strong interfacial reactions with silicon-based cores, resulting in uniform reaction products and pits across the entire surface of turbine blades. At the local core-superalloy interface, reactants diffuse into the metal layer to a depth of approximately 30-60 μm, which correlates strongly with the directional solidification time of the superalloy in different blade regions. Y and Al are predominant in interface reactions, yielding Al2O3, YAlO3, and Y3Al5O12 as primary products, which vary with directional solidification time. However, no active element Hf in the superalloy was found to participate in these reactions. During the casting of single crystal blades, active elements in the superalloy tend to react with ceramic materials, leading to surface defects such as pits on the inner blade surface, significantly affecting surface quality and mechanical properties. The duration of contact between the superalloy melt and ceramic material largely influences the extent of interfacial reaction, thereby impacting blade surface quality.