Effect of interdiffusion on mechanical and thermal expansion properties at high temperature of a MCrAlY coated Ni-based superalloy

Free-standing microtensile specimens were extracted from the substrate and the interdiffusion zone of a MCrAlY coated nickel-based single-crystal superalloy. Testing of these specimens was conducted at elevated temperatures, up to 1100 °C under controlled atmosphere, to assess the tensile and thermal expansion properties of the interdiffusion zone materials. These properties were measured and found to lie between the properties of the substrate and those of the coating. The poor mechanical strength of the interdiffusion zone evidenced its non-load bearing contribution to the system for uniaxial creep loading at high temperature representative of service conditions. It was also shown that the fabrication process of MCrAlY coated nickel-based superalloy affects the mechanical properties of the system due to the presence of voids and non-adherent grit-blasting particles within the interdiffusion zone.