DIFFUSION BRAZE A NI-BASED SINGLE CRYSTAL ALLOY: MECHANICAL PROPERTIES AND MICROSTRUCTURE

摘要

Single crystal (SC) alloys are increasingly being used to make advanced aero engine components to meet the requirements of high efficiency and high operation temperature. Since it is more expensive to produce SC alloy components, it is necessary to investigate an effective repair method to extend the component service life and further reduce the cost. High temperature diffusion braze is known to be effective in repairing cracks and surface erosion of service components as it introduces less thermal stress and distortion than welding methods. This method is especially effective in repairing stationary components. However, commonly practiced diffusion braze heat treatment for Ni based alloy components significantly alters Ni based SC alloy original microstructure and results in a dramatic change in mechanical properties. This paper presents a concept of developing an alternative high temperature braze process on Ni based SC alloys. The resulting microstructure and properties will be discussed.