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采用 2kW的CO2 激光器 ,在共晶型的Al_Si合金上熔覆Al_Fe青铜涂层 ,会产生一个特殊的过渡区。用有拉伸平台的剑桥S2 5 0MK3型SEM ,测试了该涂层的结合强度。并研究了该特殊过渡区中的断裂行为。结合强度主要受激光束扫描速率的影响 ,即扫描速度从 6mm·s-1提高到 14mm·s-1时 ,涂层结合强度也线性增加。但扫描速率超过 14mm·s-1时 ,涂层结合强度反而明显下降。动态观察断裂过程 ,发现裂纹的起点在针状组织层 (富CuAl2 层 )内。相比而言 ,裂纹扩展易于在富CuAl2 层进行。最后说明了扫描速率对结合强度影响的原因
Using a 2 kW CO2 laser, Al-Fe bronze coatings are eutectic on Al_Si alloys, creating a special transition zone. The bonding strength of the coating was tested using a Cambridge S250MK3 SEM with a tension platform. And studied the fracture behavior in this special transition zone. The bond strength is mainly affected by the scanning rate of the laser beam, ie, when the scanning speed is increased from 6mm · s-1 to 14mm · s-1, the bonding strength of the coating also increases linearly. However, when the scanning rate exceeds 14mm · s-1, the bonding strength of the coating decreases significantly. Dynamic observation of the fracture process found that the starting point of cracks in the acicular tissue layer (CuAl2-rich layer). In contrast, crack propagation is easily performed on Cu-rich layers. Finally, the reason why the scanning rate affects the bonding strength is explained