Microstructure modelling of coated single-crystal Ni-based superalloys

Market-driven requirements for better performance of gas-turbine engines are the main drive towards the development of more advanced Ni-based superalloy/coating systems. The durability of such coated components is a crucial issue faced by the power generation and the aircraft industries, because coating life mainly controls the refurbishment and replacement of many engine parts, such as blades. Coated systems undergo a number of microstructural changes as a result of thermal exposure, which need to be understood for the creation of accurate microstructure-based life-prediction models. This work was mainly concerned with the evolution of the microstructure in both the parent material and the coating as a function of temperature and time in a number of single-crystal Ni-based superalloys, coated with an MCrAlY coating. The microstructural changes occurring at various time/temperature conditions were studied using thermodynamic equilibrium calculations, scanning electron microscopy and energy dispersive X-ray analysis. [Continues.]