Abstract
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.
Highlights
Due to the excellent properties, such as high strength to weight ratio, high conductivity of electricity, good formability, non-ferromagnetic property and high corrosion resistance, aluminum alloy has an extensive application in many fields, including automobile, ship, aerospace, aviation, sensor and architecture, etc. [1,2,3,4]
Due to the open-end design of the pattern, a roughness structure with complicated morphology can be prepared on the surface by this method
From the micro-scale structure formation schematic, it can be found that the material of surface layer is melted rapidly when the laser beam continuously irradiates the surface, leading to the formation of a molten pool
Summary
Due to the excellent properties, such as high strength to weight ratio, high conductivity of electricity, good formability, non-ferromagnetic property and high corrosion resistance, aluminum alloy has an extensive application in many fields, including automobile, ship, aerospace, aviation, sensor and architecture, etc. [1,2,3,4]. Because of the distinctive surface microstructure, plants and animals exhibit various peculiar characteristics [9,10,11]. Micron-sized grooved scales growing on shark skin are interlocked to form a natural non-smooth surface. The grooved scales can reduce vortices formation and lift the vortices off the surface [13]. Through constructing a specific microstructure on a material surface, can the properties of the material be improved, and unique function (superhydrophobicity, self-cleaning, anti-icing, light trapping, etc.) can be given to the material [14,15,16]. The shortcomings of Al alloy can be overcome by preparing specific microstructure on the surface, which attractes much attention [17,18]. Great effort has been focused on constructing rough structure on
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
