稀土镁合金的YAG激光快速熔凝研究

Rapid Solidification Behavior of RE-containing Magnesium Alloys Induced by Laser Surface Remelting

Mg及其合金由于密度低、加工性能好和比强度高而在轻金属中占有较大的比重。其差的耐蚀性成为其广泛应用的最大障碍。研究采用激光表面处理的办法对铸态的ZM2、ZM5和ZM6合金进行了提高耐蚀性和显微硬度的实验。实验采用500W Nd:YAG脉冲激光器进行重熔和快淬ZM2、ZM5和ZM6合金表面。对激光表面处理区的显微组织与原基材的组织采用金相显微镜和扫描电镜进行了对比观察。采用阳极动电位测试的办法对激光处理区和基材放在NaCl溶液中进行了耐蚀性表征,经激光处理后耐蚀性得到提高。

Mg and its alloys occupy a prominent position due to its low density, excellent machinability and high specific strength. Poor corrosion resistance is a major obstacle in widespread application of Mg alloys. In the present study, an attempt was made to improve the corrosion resistance and microhardnes of cast Mg alloys ZM2, ZM5 and ZM6 were subjected to laser treatments. A 500W pulsed Nd：YAG laser was used to melt and rapidly quench the surface of the cast ZM2, ZM5 and ZM6 alloy. Comparison of the laser treatment surface microstrueture with the bulk microstructure, as observed by reflected optical microscope and scanning electron microscope（SEM） demonstrates significant alternations. Anodic polarization tests of the laser treated and untreated specimens in sodium chloride （NaC1） have suggested a variation in corrosion behavior with improvements in corrosion resistance.