激光熔覆金属陶瓷细晶复合涂层晶粒细化行为研究

Research on Behavior of Grain Refinement in Metal-ceramicSurface Fine Composite Coating by Laser Cladding

选用合适的激光工艺参数 ,利用激光熔覆工艺在中碳钢表面制备了原位自生 Ti B2 /Fe金属陶瓷细晶复合材料涂层 ,涂层中还含有少量的 Fe2 B,Ti B等硬质相 ,涂层组织较基体显著细化。研究表明 ,晶粒细化行为与激光熔覆非平衡快速凝固过程以及原位自生细小硬质颗粒增加非均质形核密切相关。此外 ,粘结金属基体中强烈的位错运动细化亚结构也促进了晶粒细化。

In-situ synthesized TiB_2/Fe metal-ceramic fine grain composite coating was fabricated on medium carbon steel by laser cladding with the optimal laser parameters, and a little amount of Fe_2B, TiB hardy phase was incorporated in the coating. Microstructure of the coating was prominently refined compared with that of the substrate. The results show that the grain refinement behavior is closely related to the non-equilibrium rapid solidification process of laser cladding and the increasing of the inhomogeneous nucleation induced by the in-situ synthesis of the fine hardy particles. In addition, refinement of the substructure caused by the strong movement of the dislocation in the bonding metal matrix accelerates the grain refinement simultaneously. The fine structure is extremely beneficial to the improvement of the coating's properties.