采用半导体激光制备了K4169高温合金熔覆涂层，并依次对涂层进行了固溶处理和时效处理；采用液氮对基板冷却的方法改变覆层在凝固过程中冷却速率，以研究冷却速率对涂层组织的影响规律；采用扫描电镜及能谱仪对涂层组织和析出相进行分析，采用差热分析仪对涂层析出相析出温度进行测定。结果表明：高的冷却速率能抑制K4169合金涂层中铌元素的偏析，同时可以抑制有害Laves相的析出；热处理可以显著提高涂层的硬度，高冷却速率下制备的涂层经热处理后硬度更高。
K4169 superalloy coating was fabricated using a diode laser. Solution and aging treatment were applied on the coating. During the solidification of the coating, the liquid nitrogen was used to cool the substrate to increase the cooling rate for studying the influence of the cooling rate on the microstructure of the coating. The microstructure and the precipitation phase in the coating were investigated by scanning electron microscopy (SEM) and energy dispersive spectroscopy. The precipitation temperatures of the phases were measured by differential thermal analysis (DTA). Results show that high cooling rate inhibited the segregation of Nb and precipitation of harmful Laves phase in superalloy K4169 coating. The microhardness of the coating was improved by the heat treatment, and the high cooling rate facilitated the improvement of the micro-hardness of the coating.
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