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Microstructural Characterization of a Ni-Al Alloyed Layer Prepared Using Laser Rapid Solidification
Y. Yang and J-D. Hu

A Ni-P electroless deposited coating with crystalline morphology was prepared on an Al substrate using Nd:YAG pulsed laser. Various laser operating parameters were experimented with and a solidification microstructure was obtained at a laser power density of 5.36 × 109 W/m2 and a scanning speed 3 mm/s. This solidified microstructure was characterized through its cross-section and showed a typical microstructure located in the upper part, the middle melted zone and the interface of meltpool with the Al substrate. The microstructure was further analysed by transmission electron microscopy (TEM). The actual solidification velocity was quantitatively determined by means of scanning electron microscopy (SEM). From the various means of observations the growth process of the Ni-Al eutectic phases was elucidated.

Keywords: Nd:YAG laser, nickel-aluminium alloy, rapid solidification, solidification microstructure, solidification velocity, eutectic growth

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