ABSTRACT A TiC/Ti6Al4V composite coating was prepared by laser cladding and the microstructure and the microhardness of different areas of the coating were studied. The results showed that an in-situ synthesis between graphene and Ti occurred during the laser cladding process and TiC was formed. At the top of the coating, the amount of TiC formed was less and it was not homogeneously distributed. In the middle of the coating, TiC was homogeneously distributed and the number of TiC particles was significantly higher. Because of the rapid cooling rate at the top, many of the nucleated TiC particles did not grow significantly. The TiC was fully grown in the middle because of lower heat dissipation and a relatively slow cooling rate; furthermore, convection of the molten pool promoted the homogeneous distribution of TiC in the middle of the cladded coating. Compared with the middle part of the coating, the coating bonded well with the Ti6Al4V matrix at the bottom of the coating. Moreover, α’ acicular martensite was formed during the rapid solidification process in the heat-affected zone (HAZ). The TiC and the α-Ti phase displayed an orientation relationship extremely close to [−2 −2 0] TiC // [2 −4 0 2] α-Ti. The hardness of the TiC/Ti6Al4V composite coating was 57% higher than that of the Ti6Al4V matrix, with the hard TiC particles played a strengthening role.

中文翻译：

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激光熔覆原位合成TiC/Ti6Al4V复合涂层的组织表征

摘要 采用激光熔覆方法制备了 TiC/Ti6Al4V 复合涂层，研究了涂层不同区域的显微组织和显微硬度。结果表明，在激光熔覆过程中，石墨烯和 Ti 之间发生了原位合成，并形成了 TiC。在涂层顶部，形成的 TiC 量较少且分布不均匀。在涂层中间，TiC 分布均匀，TiC 颗粒数量明显增多。由于顶部的快速冷却速度，许多成核的 TiC 颗粒没有显着生长。TiC在中间完全生长，因为散热较低，冷却速度相对较慢；此外，熔池的对流促进了 TiC 在熔覆层中间的均匀分布。与涂层中部相比，涂层与涂层底部的Ti6Al4V基体结合良好。此外，α'针状马氏体在热影响区（HAZ）的快速凝固过程中形成。TiC和α-Ti相显示出非常接近[-2 -2 0] TiC // [2 -4 0 2] α-Ti的取向关系。TiC/Ti6Al4V复合涂层的硬度比Ti6Al4V基体高57%，硬质TiC颗粒起到了强化作用。α' 针状马氏体是在热影响区 (HAZ) 快速凝固过程中形成的。TiC和α-Ti相显示出非常接近[-2 -2 0] TiC // [2 -4 0 2] α-Ti的取向关系。TiC/Ti6Al4V复合涂层的硬度比Ti6Al4V基体高57%，硬质TiC颗粒起到了强化作用。α' 针状马氏体是在热影响区 (HAZ) 快速凝固过程中形成的。TiC和α-Ti相显示出非常接近[-2 -2 0] TiC // [2 -4 0 2] α-Ti的取向关系。TiC/Ti6Al4V复合涂层的硬度比Ti6Al4V基体高57%，硬质TiC颗粒起到了强化作用。