Cr/WC激光表面改性梯度层组织及磨损行为

用5kWCO2激光器对先后预置不同成分合金粉末的铸造铝硅合金表面进行2次激光扫描，制备了Cr/WC激光表面改性梯度层，并对其显微组织进行了分析，结果表明，在梯度层表面产生了大量的Al9Cr4化合物，且有更多的硅元素固溶在α-Al中，增加了固溶强化的作用，自表面至基体激光改性梯度层的显微硬度呈现明显的连续变化趋势，而单次激光表面改性层与基体之间的显微硬度值则有一突变，微动磨损实验表明，激光改性后的表面抗微动磨损的能力增强，磨损机制不同于铝硅合金基体，而表现出较好的抗粘着损伤性能。

Microstructures and Tribological Behavior of Cr/WC Laser Modified Gradient Layer on Cast Al-Si Alloy

The Cr/WC gradient layers on cast Al Si alloy were obtained by twi remelting the preplaced alloy coatings using a CO 2 continuous transverse flow laser beam with maximum power of 5 kW. The microstructures of coatings were investigated. It is shown that there are more Al 9Cr 4 laths in laser modified gradient layer than in single laser surface alloying coating. More Si are dissolved in the modified gradient layer. The microhardness of laser modified gradient layer shows a gradual change from the surface to the substrate. However, the microhardness of single laser surface alloying coating is different distinctly from that of the substrate. The laser modified layers have better fretting wear resistance than that of the substrate, and there are different wear mechanism among them. The laser modified layers show the better resistance of adhesion and deformation.