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In-Situ Reactive Processing of NI/Tic Functionally Gradient Materials by Direct Laser Fabrication
Yaomin Wang, Jiandong Hu, Xiaolong He, Hongying Wang, Zuoxing Guo and Yuxin Li

Direct laser fabrication (DLF) has been used to deposit functionally gradient materials (FGM) Ni/TiC with compositions changing from pure Ni to Ni plus TiC 90 vol. % on a low carbon steel substrate. TiC particles were produced by an in-situ reaction of titanium and graphite during the laser deposition, rather than TiC particles being directly injected into the laser melted pool. The chemical composition, microstructures and micro-hardness distribution were analysed using X-ray diffraction (XRD), scanning electron microscope (SEM) with X-ray energy disperse spectrum (EDS) and Vickers hardness tests. The results showed that the multiple layer deposition consisted of the TiC and Ni phase, which indicated that TiC was synthesised by an in-situ reaction. Furthermore, the micro-hardness also exhibited a gradient with the maximum value of 2350 Hv0.3.

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