Oxidation mechanism of a nanocrystalline NiCrAlYSiHfN/AlN multilayer coating

摘要

A multilayer coating with alternate NiCrAlYSiHfN/AlN nanocrystalline layers was prepared by dual-magnetron reactive-sputtering. The NiCrAlYSiHfN layers comprised gamma-Ni, hcp-AlN, CrN and Cr2N while AlN layers comprised hcp-AlN and metallic Al. The k(p) of the alumina scale is equal to that of alpha-Al2O3 on beta-NiAl alloy. The alumina scale comprised alternate coarse- and fine-grained alumina sublayers with a few dispersed Ni(Cr) particles. Degradation of the multilayer coating, including partial decomposition of the AlN layers and precipitation of large-grained AlN within the NiCrAlYSiHfN layers, was observed. Inter-diffusion with the triple-layer structure in the IDZ between the coating and the substrate occurred.