| With the development of aviation, there is an urgent demand for lightweight materials. In comparison with ordinary aluminum alloys, aluminum lithium have advantages of low density, high specific strength and rigidity, good cryogenic property, decay resistance and excellent superplasticity property. In addition, the cost of lightweight materials is lower than that of resin matrix composite, thus is considered as the most ideal lightweight materials with high strength in the aerospace industry towards the 21st century. Broadly applied in aluminum alloys, rare earth elements, if added into alloy, can remove impurities, improve plasticity, strength, rigidity and decay resistance. Aluminum lithium in industry is generally prepared by adopting casting metallurgy and powder metallurgy approaches. This paper adopts molten salt electrolysis to directly prepare Al-Li rare earth alloy and makes further research on the electrochemical behavior of metal ions.This paper studies the electrochemical behavior of aluminum and lithium ions and the preparation of alloy of aluminum and lithium in LiCl-KCl-AlCl3 and LiCl-KCl molten salt systems. In cyclic voltammetric curve, the cathodic reduction peak potential does not change with the scan rate at a low scan rate; while the peak potential moves at a higher scan rate, which suggest that the oxidation and reduction process of aluminum is quasi reversible. And a further analysis of the relationship between the peak potential and the scan rate shows that the reduction process of aluminum ion is a diffusion control step. The reduction process of aluminum ion measured by squarewave voltammetry includes three electronic reactions in one step. An analysis of chronoamperometry and chronopotentiometry further proves the conclusion reached by cyclic voltammetry that the reduction process of aluminum ion is a diffusion control step. Diffusion coefficients measured by chronopotentiometry and chronoamperometry are 2.34×10-5 cm2·s-1 and 9.0×10-5 cm2·s-1 respectively. As the concentration of the aluminum ion increases, the potential under which aluminum is generated through aluminum reduction moves positively. In the study of the electrochemical behavior of lithium ion, we can reach the conclusion that cathodic reduction process is the irreversible process by adopting chronopotentiometry. The analysis of aluminum lithium XRD shows that there are mainly Al2Li3, Al4Li9 andβ-Li phase in alloy; the phase composition of the alloy can be changed by regulating the density of the current. An analysis by adopting SEM and EDS shows that aluminum in electrolysate is not well-distributed in alloy. An ICP analysis shows that the desired alloy can be prepared by regulating the current density and the concentration of aluminum chloride in aluminum lithium.This paper studies the electrochemical behavior of Pr ion in LiCl-KCl-AlCl3-Pr6O11 fused-salt system and the preparation of rare earth alloy. Pr6O11 is difficult or even can not be electrolyzed in LiCl-KCl fused-salt system due to the low solubility, but can be partially chlorinated by reacting with AICl3, increasing its solubility in molten salt system, thus Pr can be electrolyzed and forms alloy with Pr6O11.Analysis of different cyclic voltammetric curves under different scan rates shows that the oxidation-reduction behavior of Pr(III) ion is quasi reversible, and further analysis shows that the reduction process of Pr ion is a diffusion control step. The reduction process of Pr ion measured by squarewave voltammetry includes three electronic reactions in one step, and Pr ion will form Pr-Al alloy with Al. An analysis by adopting SEM and EDS shows that the alloy mainly contains two sections, and one is gray and the other is relatively dark; the formers of alloy are mainly Pr3Al11 intermetallic and Pr, and the latter is dark due to formation of Al phase and Al-Li intermetallic. A further analysis of the alloy shows that the Al is well-distributed, while Pr is not in alloy. |
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