激光冲击AZ31镁合金抗腐蚀性能研究

利用钕玻璃脉冲激光对AZ31镁合金表面进行激光冲击处理，金相显微镜(OM)和透射电子显微镜(TEM)微观组织表明激光冲击波导致镁合金表面层(强化层约0.8 mm)产生超高应变速率的塑性变形，晶粒内部存在大量位错和孪晶，高密度位错相互缠结,并与孪晶相互交叉导致晶粒细化。镁合金冲击表层硬度比基体提高约58%，表面残余压应力达120 MPa。在质量分数为3.5%NaCl溶液中，采用动电位扫描技术和慢应变速率拉伸应力腐蚀试验研究其冲击后的腐蚀行为，结果表明激光冲击后自腐蚀电位提高，腐蚀电流增大，抗腐蚀性有所降低，但激光冲击后镁合金抗应力腐蚀性能提高。

Abstract

AZ31 magnesium alloy is processed by Ndglass laser with the wavelength of 1064 nm and pulse width of 23 ns. Optical microscope (OM) and transmission electron microscope (TEM) show that ultrahigh strain rate plastic deformation induced by laser shock wave takes place at the surface layer and results in extensive formation of dislocations and twins. High density dislocations tangle and intersect with twins lead to the refinement of grains. The micro-hardness of surface layer induced by laser shock processing increases by up to 58 % and the compressive residual stress on the surface of laser shocked area reaches up to 120 MPa. The corrosion behavior of AZ31 in 3.5% NaCl solution is investigated using potentiodynamic scanning technique and the slow strain rate test (strain rate up to 1×10-6). The experimental results show that the corrosion resistance of AZ31 magnesium alloy by laser shock processing reduces due to the rise of the corrosion potential and the increment of corrosion current. However, the stress corrosion resistance of magnesium alloy after laser shock is improved greatly.

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李兴成, 张永康, 卢雅琳, 陈菊芳, 周金宇. 激光冲击AZ31镁合金抗腐蚀性能研究[J]. 中国激光, 2014, 41(4): 0403002. Li Xingcheng, Zhang Yongkang, Lu Yalin, Chen Jüfang, Zhou Jinyu. Research of Corrosion Resistance for AZ31 Magnesium Alloy by Laser Shock Processing[J]. Chinese Journal of Lasers, 2014, 41(4): 0403002.

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