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To overcome the disadvantages of comparatively poor surface hardness and deprived resistance against wear of Ti–6Al–4V alloy, the protective NiTi coatings are fabricated at different processing parameters by laser‐directed energy deposition (LDED). This work presents a comprehensive study of deposition morphology, phase constituents, microstructural evolution, composition distribution, and mechanical properties of as‐fabricated NiTi deposition tracks. The relationship among processing parameters and deposition morphology, phase constituents, and mechanical properties is established. The microstructural evolution mechanism and the composition distribution on the cross section of deposition tracks are revealed. Results show that the deposition tracks are successfully formed under all laser processing parameters, and the dilution ratio increases with the increase in laser power and scanning speed. The deposition tracks consist of NiTi2, NiTi, and α–Ti. According to the microstructural analysis, planar crystals are formed between the substrate and the deposition tracks, and columnar and equiaxed dendrites are found in the deposition tracks. The average microhardness increases continuously with the increase in laser power. The deposition track prepared at laser power of 1400 W has the highest average microhardness of 732.45 HV0.2. The deposition track at this laser power exhibits excellent wear properties, with a wear rate of 2.25 × 10−6 mm3 Nm−1.

Although increasing the content of ceramic reinforcement in metal matrix composites can improve some mechanical properties of processed parts, it brings significant challenges to forming technologies such as laser additive manufacturing. In this study, the high-content 60 wt. % TiC reinforced Inconel 718 composites were fabricated by laser-directed energy deposition (LDED). The influence of the laser energy density ( E) on the forming quality, microstructure development, and mechanical properties of the high-content TiC/Inconel 718 composites was investigated. It revealed that a smooth and continuous TiC/Inconel 718 deposition layer was fabricated at a proper E of 144.44 J/mm2. It is identified by x-ray diffraction that the high-content TiC/Inconel 718 composites contained two phases of Ni-Cr-Fe and TiC, and the Ni-Cr-Fe phase is the matrix phase of Inconel 718 superalloy. During the LDED process, the TiC particles melt and then precipitate without any phase changes. With increasing laser energy input, the TiC grain morphologies gradually experienced successive changes from an irregular shape to significantly refined and smoothened as an octahedron shape, and then to further refined as a near-octahedral shape with the growing tips. The dispersion state of the TiC reinforcing particles was homogenized due to the efficient Marangoni convection within the molten pool. At the optimized E of 144.44 J/mm2, the high-content TiC/Inconel 718 composite showed a relatively high average microhardness of 495.08 HV0.5, a low average coefficient of friction of 0.65, and a wear rate of 0.72 × 10−4 mm3/(N m). This research provides a fundamental understanding of high-content ceramic reinforced nickel matrix composites by laser-directed energy deposition.

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