Electrochemical study on preparation of Mg-Li-Yb alloys in LiCl-KCl-KF-MgCl2-Yb2O3 melts

International Materials Reviews

Wang

et al. 2014

265

Magnesium-lithium base alloy is one of the lightest metallic engineering materials with a density of 1?35-1?65 g cm 23 , which is referred to as superlight materials. It has become an attractive material in the fields of aerospace, automobiles, portable electronics, etc. In this paper, the developing history and recent progress of superlight magnesium-lithium base alloys are reviewed. The progress on molten electrolysis preparation, processing technologies and surface processing technologies are introduced, and future research directions are suggested based on the current research progress.

Section: Codeposition Of Mg-li-res (Rare Earths) Alloysmentioning

confidence: 99%

Recent progress in magnesium–lithium alloys

International Materials Reviews

Wang

et al. 2014

265

“…Our group has prepared Mg-Yb and Mg-Li-Yb alloys film on Mg electrodes 20,21 in molten chlorides, which needs pure Mg. On inert W electrodes 22 , our group has prepared Mg-Li-Yb alloy from LiCl-KCl-KF-MgCl 2 -Yb 2 O 3 melt. The co-reduction mechanism of Mg(II), Li(I) and Yb(III) ions was not investigated.…”

mentioning

confidence: 99%

Fabrication of Yb-Rich Mg–Li–Yb Alloys via Co-Reduction of Mg, Li and Yb

Zhang

et al. 2014

J. Electrochem. Soc.

Anhydrous K 3 YbCl 6 was obtained via solid-phase reaction from Yb 2 O 3 with NH 4 Cl and KCl as chlorination agents. Electrochemical behaviour of ytterbium ions was investigated in LiCl-KCl-MgCl 2 -K 3 YbCl 6 melt at 903 K on W electrodes. The signal corresponding to Mg 2 Yb intermetallic compound was detected at the potential close to that of the formation of Mg-Li alloy. Bulk Mg-Li-Yb alloys, characterized by X-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscopy (SEM), were prepared via electrochemical co-reduction of Mg, Li and Yb on W electrodes. Yb-rich Mg-Li-Yb alloys with different constituents were obtained via the change of the concentration of K 3 YbCl 6 .The extensive application of light alloys to substitute for conventional denser engineering materials not only relieves the energy crisis but also alleviates environmental pollution. Mg and Li, whose densities are 1.738 and 0.534 g cm −3 , can form Mg-Li alloy with low density (1.35-1.65 g cm −3 ), respectively. Mg-Li alloy is known as the lightest metallic structural material, which is also called superlight alloy. Moreover, due to its high specific stiffness, high electrical and thermal conductivities, Mg-Li alloy is increasingly utilized as structural materials in the fields of aerospace, weapons and automobiles industries. 1-4 Whereas, poor thermal stability and corrosion resistivity limit the widespread application of Mg-Li alloy. Rare earth (RE) elements and their alloys with a light metal (i.e. Al, Mg) have been widely used as additive to obtain high-performance Mg-Li based alloys. [5][6][7][8][9][10] Generally, the method for fabrication of Mg-Li-RE master alloys is primary mechanical alloying, which requires pure Mg, Li and RE metals leading to high pollution, high-energy consumption and high cost. Additionally, for variable valence rare earth elements it is impossible to obtain their pure metals via reduction of their halides using Ca or Li as a reducer because it can form stable bivalent halides. To overcome these problems, molten salt electrochemical process has been widely investigated for the preparation of rare earth alloy for its easy mass production and simple procedure. In molten salt, a feasible route to obtain RE metals is directly alloying with other metals to form corresponding intermetallics in molten chlorides or fluorides on inert and reactive electrodes. 11-15 This is because the formation potentials of intermetallic compounds locate between the deposition potentials of each pure metal, 16,17 which are usually much more positive than those of common solvents (LiCl-KCl, NaCl, CsCl). Massot and his group 16,17 have successfully obtained Al-Sm, Al-Nd and Al-Ce alloys via co-reduction of Al and RE (RE=Sm, Nd and Ce) in molten fluorides on inert electrodes. Castrillejo et al. 18 have obtained Al-Sm alloys via potentiostatic electrolysis on Al electrodes in LiCl-KClAlCl 3 -SmCl 3 melts. Nohira et al. 19 have prepared Nd-Ni alloys in molten NaCl-KCl-NdCl 3 on Ni electrodes.Our group has prepared Mg-Yb and...

“…Furthermore, for variable valence rare earth element, alloy preparation via co-reduction is another method to deposit them on inert electrode in molten salt. Zhang et al 29 have obtained Mg-Li-Yb alloy via co-reduction of Mg, Li and Yb under galvanostatic electrolysis on Mo electrode from LiCl-KCl-KF-MgCl 2 -Yb 2 O 3 melts. Castrillejo and co-workers 26 have reported the formation of Al-Yb alloy in LiCl-KCl-AlCl 3 -YbCl 3 system on inert (W) electrodes.…”

mentioning

confidence: 99%

Electrochemical Preparation of Quarternary Mg–Li–Al–Yb Alloy from Yb₂O₃Assisted by AlCl₃in LiCl–KCl–MgCl₂Melt

Zhang

et al. 2013

J. Electrochem. Soc.

Self Cite

This work presents a study on direct preparation of quarternary Mg-Li-Al-Yb alloys in LiCl-KCl-MgCl 2 -AlCl 3 -Yb 2 O 3 melt on W electrodes at 923 K. The electrochemical formation of intermetallics was investigated by electrochemical techniques of cyclic voltammetry and chronopotentiometry. The results showed that the deposition potential of Mg was a little more positive than that of Al-Yb alloy. The signals related to the formation of ternary Mg-Al-Yb intermetallics were detected in the melt. Quarternary Mg-Li-Al-Yb alloys were prepared via co-reduction of Mg(II), Li(I), Al(III) and Yb(III) on W electrodes at 923 K. Different intermetallics were identified via X-ray diffraction (XRD), and Al 2 Yb was found to be a stable phase in Mg-Li-Al-Yb alloys. The morphology and micro-zone chemical analysis of the bulk Mg-Li-Al-Yb alloys were characterized by optical microscopy (OM) and scanning electron microscopy (SEM) equipped with energy dispersive spectrometry (EDS). Moreover, the corrosion resistance property of Mg-Li-Al-Yb alloy was investigated in 3.5 wt% NaCl via potentiodynamic polarization.