Influence of Deposition Temperature on the Phase Structureand Morphology of Aluminide Coatings

Four types of aluminide coatings were fabricated by chemical vapor deposition(CVD)at differentdeposition temperatures(950 ℃,985 ℃,1020 ℃ and 1050 ℃).X-ray diffraction(XRD),scanning electronmicroscopy(SEM)and energy dispersive spectroscopy(EDS)were used to investigate the phase structure,morphology and composition of the aluminide coatings.The results show that the phase structure,morphology andcomposition of the aluminide coatings are strongly influenced by the deposition temperature during CVD.The higherthe deposition temperature,the easier the formation of pureβ-NiAl phase.With the increase of the depositiontemperature,the surface of the coatings became smooth and dense,while the ridges along grain boundariesapproached to be flat in a certain extent.Large numbers of elements of Cr,Mo and W within diffusion zone can forma thin film layer as diffusion barrier.