(1. 江蘇科技大學 材料科學與工程學院，鎮(zhèn)江 212003；
2. 重慶長征重工有限責任公司，重慶 400083；
3. 湘電風能有限公司，湘潭 411102)
摘 要: 研究了時效溫度對選區(qū)激光熔化成形高Mg含量AlSiMg1.4合金組織和力學性能的影響。結果表明：SLM沉積態(tài)樣品具有典型的熔池狀顯微組織，熔池內部為貫穿的柱狀晶，熔池邊界為等軸晶，晶粒內部存在胞狀亞結構。Mg含量的增加有效提升了合金α(Al)基體中Mg的固溶量，有利于沉積態(tài)AlSiMg1.4樣品中Mg-Si團簇的形成及直接時效樣品中Mg-Si納米強化相的析出，從而有效提升了合金的強度。樣品經150 ℃直接時效處理2 h后，其屈服強度和抗拉強度分別超過320 MPa和530 MPa，優(yōu)于傳統(tǒng)SLM成形Al-Si-Mg合金。由于不同沉積方向上熔道分布和胞狀亞結構尺寸的不同，導致沉積態(tài)樣品和150 ℃時效態(tài)樣品具有明顯的力學性能各向異性。當時效溫度增加至300 ℃和400 ℃時，由于不同沉積方向樣品的顯微組織逐漸趨同，使得樣品的力學性能各向異性逐漸消失，但網格狀富Si組織的分解導致樣品的強度大幅降低。
關鍵字: 選區(qū)激光熔化；AlSiMg1.4合金；顯微組織；力學性能；各向異性
（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
