1. An improved preparation method of core-shell Al@Sn-Bi microspheres and its microstructure formation mechanism.
- Author
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Chen, Huan, Bai, Jianlei, Liu, Yao, Mo, Zhaojun, Wang, Junfeng, and Shen, Jun
- Subjects
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MICROSPHERES , *HEAT treatment , *THERMOPHORESIS , *MICROSTRUCTURE , *INTERMETALLIC compounds , *OSTWALD ripening - Abstract
This paper presents an improved method for achieving controllable preparation of the composition and size of the monotectic alloy core-shell structure microspheres. This advancement is expected to enhance the commercial application of monotectic alloy core-shell structure microspheres. By installing a heating device at the top of the drop tube in the pulsated orifice ejection method setup, we achieved in-situ heat treatment of falling droplets, resulting in the successful preparation of Al 45 (Sn 42 Bi 58) 55 core-shell structure microspheres. Furthermore, we investigated the formation mechanism of the Al@Sn-Bi core-shell structure. Nine sets of Al-Sn-Bi microspheres with varying in-situ heat treatment temperatures were prepared. Analysis via X-ray diffraction and transmission electron microscopy revealed that the microspheres consisted of Al-rich, Sn-rich, and Bi-rich phases, without any intermetallic compounds. Scanning electron microscopy results indicated that as the in-situ heat treatment temperature increased, the structure of the Al-Sn-Bi microspheres transitioned from irregular to regular core-shell configurations. This suggests that higher heat treatment temperatures prolong liquid phase separation time, leading to increased repetition of Marangoni motion within the droplet, Ostwald ripening of the minor phase droplets, and Soret effect of the matrix phase. However, at temperatures exceeding 700 °C, the solidification rate of alloy droplets decreased, causing the Al-rich phase core to deviate from the center and form a crescent structure due to Stokes motion. [Display omitted] • A method is provided for the controllable production of monotectic alloy microspheres which have a core-shell structure. • Core-shell structure Al@Sn-Bi microspheres were prepared by the pulsated orifice ejection plus in-situ heat treatment. • Performing the microstructure evolution process of the core-shell structure Al@Sn-Bi microsphere. • Using TEM to observe the interface between Al and Sn, which composed of amorphous and nanocrystalline. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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