应用“团簇+连接原子”模型，基于合金液-固局域结构相容性和金属选区激光熔化(SLM)工艺熔体急冷的技术特性，设计高Mg含量SLM专用AlSiMg1.5合金新成分，系统研究时效温度和时间对SLM成形AlSiMg1.5合金显微组织和力学性能的影响。结果表明，通过调整工艺参数，可获得近乎全致密的SLM成形样品。当时效温度为300 ℃时，随着时效时间的延长，SLM成形样品岛状富Al组织中过固溶Si逐渐析出长大，网格状富Si组织逐渐分解球化，样品的硬度和压缩屈服强度逐渐降低，塑性明显增加。当时效温度为150 ℃时，不同时效时间下SLM成形样品的显微组织没有发生明显变化，但硬度和屈服强度随时效时间的延长先增大后略有降低。SLM成形AlSiMg1.5样品经150 ℃时效处理后的最大显微硬度和压缩屈服强度分别为(169±1) HV和(453±4) MPa，样品延伸率超过25%。本工作设计获得了成形性和力学性能优异的SLM专用铝合金新成分Al_91.0Si_7.5Mg_1.5 (质量分数，%)。

Using complex shapes and precise structural parts is becoming a strong trend in modern advanced manufacturing. However, traditional manufacturing technology hardly achieves the complex geometric parts directly. Selective laser melting (SLM) is an advanced manufacturing technology for metallic materials, enables production parts with complex geometry combined with the enhancement of design flexibility. The cooling rate of molten pool can reach 10³~10⁶ K/s during the SLM process. In this case, the solid solubility of the alloying elements in the matrix can be greatly enhanced. Aluminum alloy has been widely used in industry. At present, the strength of SLM-formed aluminum alloys is far lower than that of high-strength aluminum alloys obtained from a traditional process. It is necessary to develop high-strength aluminum alloy composition based on SLM technical characteristics. The present study is devoted to design high-strength AlSiMg1.5 aluminum alloy specifically for SLM using the local structure model based on the liquid-solid structural compatibility of the alloy and the technical characteristics of the liquid quenching in SLM. The effect of the ageing treatment on the microstructure, the hardness, and the compressive properties of the SLM-formed AlSiMg1.5 alloy was systematically studied. Almost completely dense samples were obtained by adjusting the parameters of SLM process. When the ageing temperature was 300 ℃, the super-solid solution Si precipitated and grew in the island-like Al-rich structure, and the reticular Si-rich structure decomposed and spheroidized gradually with the increases of ageing time of SLM-formed AlSiMg1.5 samples. In this case, the hardness and the strength of the samples decreased, but the elongation increased significantly. The microstructures of the SLM-formed AlSiMg1.5 samples did not change obviously when the ageing temperature was 150 ℃. But the hardness and yield strength of the samples significantly increased first and then decreased slightly. The maximum microhardness and compressive yield strength of SLM-formed AlSiMg1.5 samples aged at 150 ℃ were (169±1) HV and (453±4) MPa, respectively, and the elongation of samples exceeds 25%. In this study, a special Al_91.0Si_7.5Mg_1.5 (mass fraction, %) aluminum alloy specifically for SLM with excellent formability and mechanical properties was designed.