Effects of ultrasound on the microstructure of Al-7Si-Sc alloy prepared via molten salt electrolysis
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摘要: Al-Si系合金在現代工業、交通等領域廣泛應用,合金元素鈧可進一步改善其加工和使用性能.采用超聲協同熔鹽電解法制備Al-7S-Sc三元合金,研究探索超聲作用對合金組織及強化相分布的影響.發現超聲協同熔鹽電解制得合金中Sc含量提高,團簇共晶硅組織和AlSi2Sc2相顯著細化,共晶硅團簇尺寸由約500降低至200 μm,減小約60%,細化后AlSi2Sc2相分布均勻.超聲協同電解法可顯著優化Al-7Si-Sc合金組織,有助于控制改善現行工藝中合金元素偏聚、組織不均勻現象.Abstract: Al-Si alloys are widely used in modern industries, transportation, and other engineering applications. Processability and mechanical properties of Al-based alloys can be improved via the addition of scandium. Sc added to Al metal for fabricating Sc-containing Al alloys using molten salt electrolysis has been recently considered as promising technology. However, alloying elements, such as Sc and Si are often unevenly distributed in such Al-based alloys. In this study, Al-7Si-Sc ternary alloy was prepared via molten salt electrolysis aided with ultrasound to investigate the effects of ultrasound on the microstructure and distribution of the strengthening phase. Electrolysis was performed on molten salts of Na3AlF6-19%KF-29%AlF3-2%CaF2 at a temperature of 800℃ and current density of 1 A·cm2, in which Sc2O3 (99.99% purity) and Al-7Si alloy served as the raw material and cathodic metal, respectively. Ultrasound (20 kHz, 200 W) was introduced into the cathode metal from the cell bottom. Sc contents in the as-prepared alloy samples were determined using inductively coupled plasma atomic emission spectrometry (ICP-AES). Microstructures of the alloy samples were characterized using optical microscope and scanning electron microscope coupled with an energy dispersive X-ray analyzer. Results reveal that ultrasound can increase Sc content in the ternary alloy prepared via molten salt electrolysis and refine the eutectic silicon clusters and the ternary AlSi2Sc2 phase. Compared with the alloys made without ultrasound aid, the silicon cluster size decreases from approximately 500 to 200 μm (~60%) and the refined ternary phase of AlSi2Sc2 uniformly distributes in the metal matrix. Results also indicate that ultrasound can considerably optimize the microstructure of Al-7Si-Sc alloy prepared via molten salt electrolysis. This process can prevent problems such as the segregation of alloying elements and uneven microstructures observed when using the traditional alloy-making process.
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Key words:
- Al-Si alloy /
- eutectic silicon /
- AlSi2Sc2 /
- ultrasound /
- molten salt electrolysis
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表 1 電解與電解-超聲處理下Al-7Si-Sc合金中鈧質量分數
Table 1. Sc mass fraction of electrolytic alloys treated with and without ultrasound ?
% 制備方法 No.1 No.2 No.3 均值 電解 1.20 1.14 1.11 1.15 電解-超聲 1.52 1.47 1.45 1.48 www.77susu.com -
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