Zhou Suyuan, Su Yang, Gu Rui, Wang Zhenyu, Zhou Yinghao, Ma Qian, Yan Ming
Department of Materials Science and Engineering Shenzhen Key Laboratory for Additive Manufacturing of High-Performance Materials, South University of Science and Technology of China, Shenzhen 518055, China.
Key Laboratory of Artificial Micro- and Nano-Materials of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China.
Materials (Basel). 2018 Dec 26;12(1):73. doi: 10.3390/ma12010073.
The influences of processing parameters such as volumetric energy density (ε) and, particularly, defocusing amount (DA) on densification, microstructure, tensile property, and hardness of the as-printed dense AlSi10Mg alloy by selective laser melting (SLM) were studied systematically. The molten pool boundaries (MPBs) were found overwhelmingly at regular and complex spatial topological structures affected by DA value to exist in two forms, while the "layer⁻layer" MPB overlay mutually and the "track⁻track" MPBs intersect to form acute angles with each other. The microstructure of MPBs exhibits a coarse grain zone near the MPBs and the characteristics of segregation of nonmetallic elements (O, Si) where the crack easily happened. The DA value (-2 to 2 mm) affected both the density and the tensile mechanical properties. High tensile strength (456 ± 14 MPa) and good tensile ductility (9.5 ± 1.4%) were achieved in the as-printed condition corresponding to DA = 0.5 mm. The tensile fracture surface features were analyzed and correlated to the influence of the DA values.
系统研究了诸如体积能量密度（ε），特别是离焦量（DA）等加工参数对通过选择性激光熔化（SLM）打印的致密AlSi10Mg合金的致密化、微观结构、拉伸性能和硬度的影响。发现熔池边界（MPB）绝大多数存在于受DA值影响的规则和复杂空间拓扑结构中，以两种形式存在，即“层-层”MPB相互重叠，“道-道”MPB相互交叉形成锐角。MPB的微观结构在MPB附近呈现粗晶区以及易发生裂纹的非金属元素（O、Si）偏析特征。DA值（-2至2毫米）影响密度和拉伸力学性能。在对应于DA = 0.5毫米的打印状态下实现了高拉伸强度（456±14兆帕）和良好的拉伸延展性（9.5±1.4%）。分析了拉伸断口表面特征并将其与DA值的影响相关联。
