Microstructure evolution of semi-solid Mg 2 Si/A356 composites during remelting process
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https://doi.org/10.1007/s41230-020-9158-7
Microstructure evolution of semi-solid Mg2Si/ A356 composites during remelting process *Yong Hu 1,2, Sheng-qi Fu 1,2, Long-zhi Zhao 1,2, Da-hao Wang 1,2, Fei Liu 1,2 1. School of Materials Science and Engineering, East China Jiaotong Uinversity, Nanchang 330013, China 2. Key Laboratory of Advanced Materials for Vehicles & Laser Additive Manufacturing of Nanchang City, East China Jiaotong University, Nanchang 330013, China
Abstract: The semi-solid processed Mg2Si/A356 composites were fabricated using a sloping plate, and the phase and morphology evolution of the semi-solid Mg2Si/A356 slurry during the remelting process was investigated. Results indicate that compared to as-cast microstructure, the size of primary α-Al phase and Mg2Si phase of semi-solid microstructure fabricated by using a sloping plate decreases and the morphology of α-Al phase becomes fine and globular. With increasing the reheating temperature and prolonging the holding time, the primary α-Al phase spheroidizes, the liquid fraction in semi-solid microstructure increases, and the Chinese script Mg2Si phase embedded in the primary α-Al phase cannot be observed. The Chinese script Mg2Si phase is distributed in the secondary α-Al phase and becomes smaller. The net-shaped eutectic phase also becomes finer after reheating. The optimum remelting parameters suitable for thixoforming in this study are remelting at 580 °C for 30 min. Key words: semi-solid; Mg2Si; aluminum matrix composites; remelting; microstructure CLC numbers: TG146.21
Document code: A
A
luminum matrix composites have wide application prospects in automotive and aerospace industries because of their high specific strength, specific modulus, as well as high wear resistance and excellent thermal stability [1-3]. However, the ductility of aluminum matrix composites is low, and the plastic deformation capacity is poor, which limits the application of aluminum matrix composites. Semi-solid metal forming method invented by Flemings in the 1970s has been rapidly developed [4-6]. It is a method taking advantage of the thixotropic behavior of alloys in the two-phase field between solidus and liquidus. The deformation resistance is low during semi-solid metal forming, which is suitable for forming aluminum matrix composites. Compared to traditional casting or forging, semi-solid metal forming has many advantages, such as extension of service life for forming die, capability of producing complex structural components, high dimensional accuracy, low production costs, and so on [7]. The above advantages derive from the non-dendritic structures of semi-solid metal. As an important semi-solid *Yong Hu Male, born in 1982, Ph. D., Associate Professor. His research interests mainly focus on light-weight metal materials and the semi-solid process. To date, he has published about 30 papers. E-mail: [email protected]
Received: 2019-12-23; Accepted: 2020-05-25 384
Article ID: 1672-6421(2020)05-384-05
metal forming method, thixoforming has attracted much atten
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