Abstract
Characterizations of laser glazed surfaces and substrate structures of nickel alloy 718 have been studied. Cross sections of laser glazed and substrate sample surfaces of nickel alloy 718 were cut to different dimensions for various tests. Morphological examinations of the sample surfaces were done using confocal laser scanning microscope. It was followed with x-ray diffraction (XRD) tests at different angles of incidents for identification of possible oxide phases in the alloy. Microstructural examinations of the alloy samples were carried out and they involved; scanning electron microscopy (SEM), electron back scatter diffraction (EBSD) and energy dispersive x-ray spectroscopy (EDX). The results of the tests from the sample morphologies show that the surfaces of the samples were covered with different oxide layers/scales. XRD results identified these oxide phases present on the sample surfaces with their various crystal systems. The results further show that as the angle of x-ray incident increased, the intensity of substrate phases increased with corresponding decrease in surface oxide phases. The results of electron back scatter diffraction from the band contrast map show that the microstructures of the laser glazed surfaces are columnar while that of the substrates are bimodal with small equiaxed grains surrounding the large grains. There was no evidence of distinct interfacial separation seen between the surfaces. The result further revealed different crystallographic plane orientations from Euler colour map and the possible slip planes corresponding to , and . From the crystallographic colour orientations, it indicated that both the substrate and laser glazed regions are partly homogeneous. Results from scanning electron microscopy (SEM) of the sample substrate revealed the microstructures and the presence of bright spot believed to be intermetallic phases of heavy metals. Consequent upon these, analysis of both surfaces show that they have similar physical and microstructural properties with no interfacial separation at their boundary regions. These indicate that both structures are compatible for engineering applications.