(华南理工大学 国家金属材料近净成形工程技术研究中心，广州 510640)
摘 要: 采用激光选区熔化(Selective laser melting，SLM)技术制备含锆Al-Cu-Mg合金，通过SEM、EBSD、TEM、拉伸实验等方法研究沉积态和热处理态试样的显微组织与力学性能。结果表明：当激光能量密度为370？J/mm3时，试样的致密度最高。原位生成Al3Zr使试样的平均晶粒尺寸细化为1.28？μm，消除了SLM成形Al-Cu-Mg合金中的热裂纹。尺寸为50~300？nm的Al3Zr亚稳态相(L12-Al3Zr)分布于基体，L12-Al3Zr可充当α(Al)非均匀形核的有效衬底，与α(Al)晶面的错配度低，也能阻碍晶界迁移，抑制晶粒长大。工艺优化后，沉积态试样的室温抗拉强度为(369±9)？MPa，伸长率为(12.4±0.6)%；T6热处理后，试样的抗拉强度提升至(485±10)？MPa，伸长率略降为(11.2±0.5)%。细晶强化和弥散强化分别主导了沉积态和热处理态试样的强度提升。
关键字: 激光选区熔化；Al-Cu-Mg合金；Al3Zr；显微组织；力学性能
（National Engineering Research Center of Near-Net-Shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640, China）
Abstract:Zr-modified Al-Cu-Mg alloy was processed by selective laser melting (SLM) technique. The microstructures and mechanical properties of as-deposited and heat-treated(T6) samples were systematically analyzed. The results show that samples with the highest density can be achieved when the energy density is 370？J/mm3. The in-situ formed Al3Zr refines the grain size to 1.28？μm and therefore eliminates the common hot tearing in SLMed Al-Cu-Mg alloys. The metastable phase of Al3Zr (L12-Al3Zr) with a size range of from 50 nm to 300？nm is observed, which is responsible for the grain refinement. L12-Al3Zr particles act as the nucleus of heterogenous nucleation of α(Al) due to their minimal mismatch. Besides, the L12-Al3Zr particles can further refine the grains by hindering the migration of grain boundaries. The ultimate strength of (369±9)？MPa and the elongation of (12.4±0.6)% are achieved for the as-deposited samples after process parameter optimization. After T6 heat treatment, the ultimate strength greatly increases to (485.2±10)？MPa with a slight decrease in plasticity (elongation of (11.2±0.5)%). The strength enhancements of the as-deposited and heat-treated samples can be mainly attributed to the Hall-Petch strengthening and the Orowan strengthening mechanisms, respectively.
Key words: selective laser melting; Al-Cu-Mg alloy; Al3Zr; microstructure; mechanical properties
