采用XRD, SEM和EDS分析了机械振动辅助激光熔覆NiCrBSi-TiC颗粒增强复合涂层中外加TiC颗粒和内生M₂₃C₆碳化物的生长形态、形成机制及其在γ-Ni固溶体间的分布特征. 结果表明, 熔池内大部分外加TiC颗粒在熔覆过程中溶解,溶解于镍基合金熔体中的过饱和Ti和C原子在冷却过程中又形成TiC颗粒, 并以共晶方式析出, 其通过M₂₃C₆型碳化物为核心异质形核, 并侧向生长; 同时, 出现以TiC为心部, 以(Ti, Cr, Ni, Fe, Si)C为外围包覆结构的复式碳化物.在振动作用下, 底部粗大枝晶状共晶组织消失, 振动引起的流体平流层使底部TiC颗粒上浮趋势减缓, 出现双颗粒和花瓣状多颗粒TiC粒子簇. 振动作用使熔覆层区域内的组织得到细化, 枝晶间网状(Fe, Ni)固溶体中Cr含量升高, TiC颗粒析出增多, 颗粒尺寸增加, 平均粒径增加超过25%. 从XRD谱可观察到, 振动作用使涂层内主要硬质相的衍射峰增强, 半高宽变宽, 表明硬质相的晶格完整性提高, 晶粒细化. 振动作用促使颗粒相均匀弥散分布于基体枝晶内和枝晶间.

The good high temperature wear resistance and corrosion behavior of particle reinforced Ni-based alloy composite coating have attracted extensive attention in material science and engineering. It is necessary to analyze the morphologic characteristics and distribution of particles in composite coating. TiC particle reinforced NiCrBSi composite coating on medium carbon steel surface was fabricated by mechanical vibration assisted laser cladding technique. According to the distribution characteristics of hard phase particles in laser cladding molten pool, the growth morphology of TiC particle and endogenous M₂₃C₆ carbide, formation mechanism and its distribution characteristics in γ-Ni solid solution were analyzed by XRD, SEM and EDS. The results showed that most of TiC particles dissolved into the melted Ni-based alloy, but some supersaturated Ti and C atoms were precipitated in the form of TiC particles eutectic during cooling process. The TiC particles lateral growth with heterogeneous nucleation way depended on M₂₃C₆ type carbide substrate. At the same time, some composite carbide core-shell structure with (Ti, Cr, Ni, Fe, Si)C encapsulated TiC were generated in the coating. Under the effect of vibrant force, the bulky branch crystal eutectic structure disappeared in the bottom of laser cladding coating, the TiC particle floatation trend slowed down with the fluid stratosphere which caused by vibratory force and high-pressure gas, and some double and petal shape TiC particle clusters were also formed. The precipitated TiC particle increases with the Cr content in the inter-dendrite reticular (Fe, Ni) solid solution, and the average particle size was increased by more than 25%. The XRD results indicated that the diffraction peak intensity and lattice integrity of the main hard phases were enhanced, the half peak width was broadened and the crystalline grain size become smaller. The mechanical vibration promoted the dispersion of particles in the matrix dendrites and inter-dendrite.