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采用激光熔覆与微弧火花沉积(ESD)工艺在定向铸造高温合金表面成功实现了外延定向复合沉积,并使用光学显微镜(OM)、扫描电镜(SEM)等对所获涂层的典型组织进行了研究。研究结果显示,定向生长区域连续、均匀,无明显缺陷;定向组织垂直于沉积界面生长,其取向与定向基体基本一致。定向柱晶宽度按定向凝固基体(～300μm)→激光接长区(～20μm)→微弧火花接长区(～1μm)梯度递减。分析表明:这种显微组织上的变化主要是凝固过程中液固界面前沿的凝固速度(R)、温度梯度(G)、热流方向等热力学因素综合作用的结果。
The epitaxial directional composite deposition was successfully achieved on the surface of the superalloy by directional laser casting and micro-arc spark deposition (ESD). The microstructure of the obtained coating was characterized by optical microscope (OM), scanning electron microscope (SEM) Study. The results show that the directional growth area is continuous, uniform and has no obvious defects. The orientation structure grows perpendicular to the deposition interface and its orientation and orientation matrix are basically the same. The width of the oriented columnar crystallites was gradually reduced according to the directional solidification matrix (~ 300μm) → laser long zone (~ 20μm) → micro arc long zone (~ 1μm). The analysis shows that the change of microstructure is mainly the result of the combination of thermodynamic factors such as solidification velocity (R), temperature gradient (G) and direction of heat flow at the front of liquid-solid interface during solidification.