激光重熔处理对铝合金微弧氧化层组织及性能的影响

采用激光重熔处理改善6061铝合金微弧氧化层的耐蚀性，采用光学显微镜、共聚焦显微镜、扫描电镜、X射线衍射仪、电化学工作站等研究了500～1000 W激光功率下微弧氧化层孔隙率、粗糙度、表面形貌、物相组成及耐蚀性能。结果表明，经过激光重熔处理后微弧氧化层主要由α-Al₂O₃和γ-Al₂O₃两相组成，随着激光功率的增加，γ-Al₂O₃向α-Al₂O₃转化的程度增加。激光功率为500～900 W时微弧氧化层孔隙率先增加后减小，但粗糙度变化不明显；1000 W时微弧氧化层鼓起、开裂，粗糙度、孔隙率增加。激光功率为900 W时微弧氧化层表面微孔孔径减小甚至闭合、裂纹数量减少，孔隙率降至最低，耐蚀性能最好。

Effect of laser remelting on microstructure and properties of micro-arc oxidation layer on aluminum alloy

Laser remelting was used to improve corrosion resistance of the micro-arc oxidation layers on 6061 aluminum alloy. The porosity, roughness, surface morphology, phase composition and corrosion resistance of the micro-oxidation layers under laser power of 500-1000 W were studied by means of optical microscope, confocal microscope, scanning electron microscope, X-ray diffractometer and electrochemical workstation. The results show that the micro-arc oxidation layer after laser remelting is mainly composed of α-Al₂O₃ and γ-Al₂O₃ phases, and the conversion degree from γ-Al₂O₃ to α-Al₂O₃ increases with laser power increasing. When the laser power is in the range of 500-900 W, the porosity of the micro-arc oxidation layer increases firstly and then decreases, but the roughness does not change significantly. When the laser power is up to 1000 W, the micro-arc oxidation layer surface becomes bulging and cracking, which makes the roughness and porosity of the layer increase. When the laser power is 900 W, the micropore size decreases or even closes, and the number of cracks is reduced, the surface porosity is minimized, the corrosion resistance is the best.