微观组织
(哈尔滨工业大学 现代焊接生产技术国家重点实验室，哈尔滨 150001)
摘 要: 采用激光-TIG复合熔注工艺，在铝合金表面制备WCp/Al表面复合材料层。通过优化激光功率、TIG电流、扫描速度和送粉率等工艺参数，可以获得0.5~4.3 mm厚的表面复合材料层。采用XRD、SEM、EDS等手段对表面颗粒强化层的微观组织和成分进行研究。结果表明：熔注层基体的微观组织为过共晶组织；熔注层不同位置的过共晶相具有不同的形貌，熔池上部主要为含有十字花状、鱼骨状、蝶状先共晶相(W1−xAlx)Cy的过共晶组织，而底部的先共晶相呈现块状形态。
关键字: 颗粒增强复合材料；铝合金；WC；激光-TIG复合；显微组织
produced by hybrid laser-TIG melt injection
（State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology,
Harbin 150001, China）
Abstract: In order to overcome the difficulties of laser melt injection (LMI) on aluminum alloys, which include high reflection of laser on aluminum, oxide film and high heat conductivity of aluminum alloy, the hybrid laser-TIG melt injection (HLTMI) was developed. WCp/Al composite layer was prepared on the surface of aluminum. Through optimization of process parameters of HLTMI, such as laser power, TIG current, scanning velocity and powder feeding rate, the MMC layers with different thicknesses ranging from 0.5 mm to 4.3 mm can be achieved. The microstructure and composition of the coatings were analyzed by means of XRD, SEM and EDS. The results show that the microstructures of MMCs layer presents a hypereutectic structure. The hypereutectic phases at different locations exhibit different shapes: the hypereutectic phase (W1−xAlx)Cy at the upside of the layer represents cross shape, fishbone-like or papilionaceous, while the preeutectic phase at the bottom of the layer exhibits massive structure.
Key words: particulate metal matrix composite; aluminum alloy; WC; hybrid laser-TIG; microstructure
