Interfacial Reaction Mechanism between Ceramic Mould and Single Crystal Superalloy for Manufacturing Turbine Blade

Single crystal superalloys are the preferred materials for manufacturing turbine blades of advanced aero-engines, due to their excellent high temperature comprehensive performance. The interfacial reaction between alloys and ceramic mould are an important factor to influence the surface quality and service performance of the turbine blade. It is very important to reveal the interfacial reaction mechanism to improve turbine blade quality and yield rate. In this paper, the interfacial reactions between DD6 single crystal superalloy and ceramic mould were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD). The results show that the main reaction products were HfO₂, Al₂O₃ and Y₃Al₅O₁₂ when the yttrium oxide powders were the prime coat materials, while alloy surface suffered undesirable sand fusion; the thicknesses of the reaction layers were over 20 μm. The reaction layer can be divided into two layers, the layer close to the alloy was mainly composed of Al₂O₃ and Y₃Al₅O₁₂, and the layer close to the mould was composed of SiO₂, Al₂O₃ and Y₃Al₅O₁₂. Avoiding the formation of Y₂O₃-Al₂O₃-SiO₂ ternary low-melts can solve the interfacial reaction between DD6 alloy and yttrium oxide mould.