Tang Mingkai, Shi Yusheng, Zhu Wenzhi, Zhang Nan, Zhang Lichao
School of Materials Science and Engineering, Huazhong University of Science and Technology, 1037 Luoshi Road, Wuhan 430074, China.
Materials (Basel). 2018 Nov 16;11(11):2297. doi: 10.3390/ma11112297.
Surface microstructure preparation offers a promising approach for overcoming the shortcomings of Al alloy, such as poor friction resistance, low hardness and weak corrosion resistance to corrosive liquid. Though many methods for the surface microstructure preparation of Al alloy have been developed, it is difficult for most of the reported methods to regulate the as-prepared microstructure, meaning that the properties of Al alloy cannot be improved efficiently by the microstructure. Thus, the application of microstructure surface of Al alloy and microstructure preparation technology is severely limited. Aimed at this issue, a simple, convenient, high-efficient, low-cost micro-scale roughness structure construction approach that is suitable for engineering application (laser micro-engraving) was developed. The as-prepared microstructure on Al alloy surface formed by laser micro-engraving was investigated systemically. The morphology and formation mechanism of the microstructure were examined. Meanwhile, the effect of laser parameters on morphology, geometrical dimensions and composition of microstructure was investigated. The results indicate that the morphology of microstructure is affected by the overlap degree of molten pool greatly. When each molten pool does not overlap with others, successive individual pits can be constructed. When each molten pool overlaps with others for one time, successive overlapping pits will form. As the overlap degree of the molten pool further increases (overlapping with others for more than one time), the successive pits can become grooved. Because of the influence of laser beam pulse frequency and scanning speed on the diameter and distance of the molten pools, the morphology and geometrical dimensions of microstructure can vary greatly with laser parameters. As the laser beam scanning speed increases, the geometrical dimensions of as-prepared microstructure reduce significantly. In contrast, with the increase of laser beam pulse frequency, the geometrical dimensions change in a complicated manner. However, the chemical composition of microstructure is slightly affected by laser parameters. More importantly, a relationship model was successfully established, which could be used to predict and regulate the geometrical dimensions of microstructure treated by laser micro-engraving. Controllable preparation of microstructure on Al alloy is realized, leading that specific microstructure can be prepared rapidly and accurately instead of suffering from long-time experimental investigation in the future.
表面微观结构制备为克服铝合金的缺点提供了一种很有前景的方法，这些缺点包括耐摩擦性差、硬度低以及对腐蚀性液体的耐腐蚀性弱。尽管已经开发出许多用于铝合金表面微观结构制备的方法，但大多数已报道的方法都难以调控所制备的微观结构，这意味着铝合金的性能无法通过微观结构得到有效改善。因此，铝合金微观结构表面及微观结构制备技术的应用受到严重限制。针对这一问题，开发了一种简单、便捷、高效、低成本且适用于工程应用的微尺度粗糙度结构构建方法（激光微刻蚀）。对通过激光微刻蚀在铝合金表面制备的微观结构进行了系统研究。考察了微观结构的形貌和形成机制。同时，研究了激光参数对微观结构的形貌、几何尺寸和成分的影响。结果表明，微观结构的形貌受熔池重叠程度的影响很大。当每个熔池不与其他熔池重叠时，可以构建出连续的单个凹坑。当每个熔池与其他熔池重叠一次时，会形成连续的重叠凹坑。随着熔池重叠程度进一步增加（与其他熔池重叠超过一次），连续的凹坑会变成沟槽。由于激光束脉冲频率和扫描速度对熔池直径和间距的影响，微观结构的形貌和几何尺寸会随激光参数发生很大变化。随着激光束扫描速度的增加，所制备微观结构的几何尺寸显著减小。相反，随着激光束脉冲频率的增加，几何尺寸以复杂的方式变化。然而，微观结构的化学成分受激光参数的影响较小。更重要的是，成功建立了一个关系模型，可用于预测和调控经激光微刻蚀处理的微观结构的几何尺寸。实现了铝合金微观结构的可控制备，这使得未来能够快速、准确地制备特定的微观结构，而无需进行长时间的实验研究。
