镁合金激光选区熔化研究进展

镁合金作为最轻的金属结构材料，在汽车制造、生物医疗等领域具有极大的应用潜力。激光选区熔化成形镁合金具有高效的制备性能、良好的成分均匀性、优异的力学性能和耐腐蚀性能，因此激光选区熔化成为一种重要的镁合金制备和改性方法。对近几年激光选区熔化镁合金的研究进展进行了综述，从激光工艺参数(激光类型、体能量密度、激光功率、扫描速度、扫描模式、层厚、扫描间距、气氛控制与进粉速度)和粉体状态(粉末形状、粒径分布、粉末对激光束能量吸收率、粉末化学成分)2个方面讨论了该工艺的关键技术;按照纯镁、非稀土镁合金体系、稀土镁合金体系的分类，对激光选区熔化成形镁及镁合金的致密度与微观结构、力学性能与耐腐蚀性能进行了总结;分析了工艺参数与合金成分两方面对该工艺成形镁合金缺陷的影响。为减少激光选区熔化成形镁合金缺陷、均匀化晶粒、溶解硬脆二次相或析出强化相进而改善合金的结构与性能，许多研究对激光选区熔化成形镁合金进行了热等静压、固溶热处理和时效热处理，总结了上述处理方式对AZ体系、WE体系与Mg-Gd体系镁合金的改善效果。最后展望了激光选区熔化成形镁及镁合金在各领域的应用前景与未来可以进行研究的方向。

Research Progress on Selective Laser Melting of Magnesium Alloy

Magnesium alloy, as the lightest metal structural material, has great potential for application in aerospace, automotive manufacturing, biomedical and other fields. The magnesium alloy formed by selective laser melting has efficient preparation performance, good composition uniformity, excellent mechanical properties, and corrosion resistance. These characteristics make selective laser melting an important method for the preparation and modification of magnesium alloys. The research progress of selective laser melting of magnesium alloys in recent years was reviewed. Firstly, the key technologies of this process were discussed from two aspects of laser process parameters (laser type, bulk energy density, laser power, scanning speed, scanning mode, layer thickness, scanning spacing, atmosphere control and powder feeding speed) and powder state (powder shape, particle size distribution, energy absorption rate of powder for laser beam and chemical composition of powder). The density, microstructure, mechanical properties, and corrosion resistance of selective laser melting formed magnesium and magnesium alloys were summarized based on pure magnesium, non rare earth magnesium alloy systems, and rare earth magnesium alloy systems. The effect of process parameters and alloy composition on the defects of magnesium alloy formed by this process was analyzed. In order to reduce defects, homogenize grains, dissolve hard and brittle secondary phases or precipitate strengthening phases in selective laser melting formed magnesium alloys and improve their structure and properties, many studies were conducted on hot isostatic pressing, solid solution heat treatment, and aging heat treatment on selective laser melting formed magnesium alloys. The improvement effects of the above treatment methods on AZ system, WE system, and Mg-Gd system magnesium alloys were summarized. Finally, the application prospects and future research directions of selective laser melting forming of magnesium and magnesium alloys in various fields were prospected.