effect of zr content on oxide-scale spallation of aluminide coating

In the present study, zirconium modified aluminide coating on the nickelbase superalloy in738lc was first created by high activity high temperature aluminizing based on the outofpack cementation method. then, zr coatings were applied to simple aluminide coatings by sputtering and heat treatment in order to study the effect of zr on the coating microstructure and oxide spallation. microstructural studies were conducted by using scanning electron microscopy (sem), energy dispersive xray spectrometry (eds), and xray diffraction (xrd) microanalysis. the results indicated that zirconium modified aluminide coating, like aluminide coating, has a twolayer structure including a uniform outer layer of nial and an interdiffusion layer in which zirconium is in a form of solid solution in the coating. furthermore, the 300nm zrcoated nial demonstrated an excellent scale adhesion, a slow oxidation rate and lower amounts of some other elements such as ti and cr in its oxide layer leading to a pure aluminide oxide layer.