Influence of Scan Velocities on Material Properties of Laser Based Coatings of Ni-Co on Ti-6Al-4V Alloy




Abstract:  In this work, laser clad Ni-Co layers were produced on Ti-6Al-4V substrates using Nd:YAG high power laser beam. Laser cladding aids the in-situ formation of a uniform clad by melting and fusing the powder with the substrate surface to form desired composition. The effects of laser scanning velocity and volume fraction of the reinforced Ni-Co powders on clad layer formation and its properties were investigated. Laser power of 750W, beam size of 3mm with argon shield gas flow rate of 1.2L/min was made constant, while the scanning velocities were varied. The microstructural analysis, phase constituents and hardness properties of Ni-Co intermetallics reinforced clads were also examined. The morphology of the resultant coatings was analyzed using X-ray diffractometry (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS). Results showed that the coatings displayed enhanced properties such as fine microstructure and good metallurgical bonding with the substrate containing minimal pores with respect to the substrate. Furthermore, the microstructure revealed the formation of various fractions of interdendritic compounds/intermetallics dispersed within the coating matrix which could be responsible for the increased hardness obtained. Ni-Co laser based coatings show promising capabilities in mitigating the pressing issues related to Ti-6Al-4V alloy.

Authors: O.S. Adesina and A.P.I. Popoola

Keywords: Laser Cladding Technique, Ni-Co, Intermetallics, and Ti6Al4V

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