利用原子力显微镜(AFM)、扫描电子显微镜(SEM)和透射电镜(TEM)对TC4 合金表面NiCrBSiC合金激光熔覆层中反应合成的TiC和TiB2形貌进行了观察, 分析了TiC和TiB2相的生长机制。结果表明, 激光熔覆反应合成的TiC相呈等轴树枝晶状, 并具有非小平面和小平面两种生长界面(当树枝晶尺寸较小时, 具有非小平面生长界面, 当树枝晶尺寸较大时, 具有小平面生长界面), TiB2相呈六棱柱状, 通常在TiC树枝晶表面异质形核, 并以小平面形式生长, 最终形成心部为TiC相外部为TiB2相的特殊复相结构。

The morphology of in-situ synthesized TiC and TiB2 in laser cladding NiCrBSiC coatings on TC4 alloy was observed by atom force microscope (AFM), scanning electron microscope (SEM) and transmission electron microscopy (TEM), and the growth mechanism of TiC and TiB2 phase was discussed. The results show that, TiC phase in the coatings is equiaxial dendrites with facet and non-facet growth interfaces (the growth interface presents non-facet for small dendrite and facet for large dendrite). TiB2 phase shows flat hexagonal prism which heterogeneously nucleates on TiC dendrite and grows with faceted mode. The special structure with TiC in the core and TiB2 in the exterior was obtained.