(1. 江苏科技大学 材料科学与工程学院，镇江 212003；
2. 重庆长征重工有限责任公司，重庆 400083；
3. 湘电风能有限公司，湘潭 411102)
摘 要: 研究了时效温度对选区激光熔化成形高Mg含量AlSiMg1.4合金组织和力学性能的影响。结果表明：SLM沉积态样品具有典型的熔池状显微组织，熔池内部为贯穿的柱状晶，熔池边界为等轴晶，晶粒内部存在胞状亚结构。Mg含量的增加有效提升了合金α(Al)基体中Mg的固溶量，有利于沉积态AlSiMg1.4样品中Mg-Si团簇的形成及直接时效样品中Mg-Si纳米强化相的析出，从而有效提升了合金的强度。样品经150 ℃直接时效处理2 h后，其屈服强度和抗拉强度分别超过320 MPa和530 MPa，优于传统SLM成形Al-Si-Mg合金。由于不同沉积方向上熔道分布和胞状亚结构尺寸的不同，导致沉积态样品和150 ℃时效态样品具有明显的力学性能各向异性。当时效温度增加至300 ℃和400 ℃时，由于不同沉积方向样品的显微组织逐渐趋同，使得样品的力学性能各向异性逐渐消失，但网格状富Si组织的分解导致样品的强度大幅降低。
关键字: 选区激光熔化；AlSiMg1.4合金；显微组织；力学性能；各向异性
（1. School of Materials Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China;
2. Chongqing Changzheng Heavy Industry Co., Ltd., Chongqing 400083, China;
3. XEMC Winpower Co., Ltd., Xiangtan 411102, China）
Abstract:In this work, the influence of aging temperature on microstructure and mechanical properties of SLM deposited high Mg-content AlSiMg1.4 alloy was systematically studied. The results show that the SLM deposited sample has a typical molten pool structure, in which the columnar grains penetrate the molten pool and the equiaxed grains exist in the molten pool boundary. The cellular substructure exists in the grains. The increase of Mg content in the sample effectively improves the solid solution of Mg in α(Al) matrix, which is conducive to the formation of Mg-Si clusters in SLM deposited samples and the precipitation of Mg-Si strengthening phases in direct aging samples, and thus effectively improves the strength of the alloy. After being aged at 150 ℃ for 2 h, the yield strength (σ0.2) and tensile strength (σb) of the samples are over 320 MPa and 530 MPa, respectively, which are higher than those of the most of the known Al-Si-Mg alloys fabricated by the SLM technique. Due to the different distribution and size of cellular substructure in different deposition directions, the as-deposited and 150 ℃ aging samples have obvious mechanical property anisotropy. When the aging temperature increases to 300 ℃ and 400 ℃, the anisotropy of mechanical properties of the samples with different deposition directions disappears due to the decomposition of cellular substructure. In this case, the strength of the samples decreases significantly, and the elongation increases greatly.
Key words: selective laser melting; AlSiMg1.4 alloy; microstructure; mechanical properties; anisotropy
