EBSD study of (110) orientation of iridium (Ir) coating on niobium (Nb) substrate by double glow plasma

(1 1 0)-Oriented Ir coating was prepared by double glow plasma technique on (2 0 0)-oriented Nb substrate. The microstructure of the coating was observed by scanning electron microscopy (SEM). The crystal orientation of the coating was determined by X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). The coating was composed of columnar grains with submicrometer size of 0.2-0.3 0.3 mu m. The thickness of the coating was approximately 6-7 mu m. The mean misorientation angles of the surface of the coating were about 38.6 degrees. The columnar Ir coating had a preferential growth orientation of (1 1 0) crystal plane by XRD and EBSD due to the initial nuclei with preferred growth on the surface of the substrate. The vigorous bombardment from the high energy ions prevented the lower energy (1 0 0) crystal face and the lowest energy (1 1 1) crystal face from generating the orientation. Only the highest energy (1 1 0) crystal face could be formed and grew up, which resulted in the preferred (1 1 0) orientation. (c) 2013 Elsevier B.V. All rights reserved.