Low inter-diffusivity γ′-base bondcoats for single crystal superalloy Rene N5.Ⅰ: Primary study of microstructures and oxidation behaviors at 1100 ℃

摘要

Three gamma'-base bondcoats, which are referred to as Al-19, Al-20 and Al-25 following their atomic percent of Al, respectively, were prepared on single crystal superalloy Rene N5 by magnetron sputtering. All the coatings exhibited excellent resistance against high temperature oxidation at 1100 degrees C. Furthermore, the coatings Al-19 and Al-20 exhibited low inter-diffusivity to the substrate, neither interdiffusion zone nor secondary reaction zone was formed during oxidation at 1100 degrees C for 300 h. A secondary diffusion zone was observed in the Al-25 coated samples probably due to precipitation of similar to 11.4 vol.% beta-NiAl in the coating during vacuum annealing at 1000 degrees C.