Cyclic oxidation behaviour of Ti3Al-based alloy with Ni-Cr protective layer
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The influence of a thin 80Ni-20Cr (at.%) protective coating on the cyclic oxidation of a Ti-24Al-11 Nb (at.%) alloy based on Ti3Al at 600 and 900 degrees C in air was investigated using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD). The results of the oxidation tests showed that deposited Ni-Cr layer provides an improved oxidation resistance due to the formation of protective oxide scale which barriers the outward Ti diffusion into the scale. In some extent surface formation of the nitride layer also prevents diffusion of alloying elements from the matrix. Although oxidation at 900 degrees C is faster than that at 600 degrees C, a remarkable reduction in mass gain of the alloy with protective coating was observed. The thickness of oxide scale on the coated samples is approximately two times less than that formed on the uncoated samples treated under the same exposure conditions (120 h). (c) 2008 Elsevier Ltd. All rights re...served.
Keywords:Ti3Al-based intermetallics / sputtered coating / XRD / cyclic oxidation / oxide scale fracture
Source:Corrosion Science, 2008, 50, 7, 1919-1925
- Ministry of Science of the Republic of Serbia