Phase lithium alloys

Metallurgy. Lithium forms alloys with numerous metals. Early uses of lithium alloys were made in Germany with the production of the lead alloy, BahnmetaH (0.04% Li), which was used for bearings for railroad cars, and the aluminum alloy, Scleron. In the United States, the aluminum alloy X-2020 (4.5% Cu, 1.1% Li, 0.5% Mn, 0.2% Cd, balance Al) was introduced in 1957 for stmctural components of naval aircraft. The lower density and stmctural strength enhancement of aluminum lithium alloys compared to normal aluminum alloys make it attractive for uses in airframes. A distinct lithium—aluminum phase (Al Li) forms in the alloy which bonds tightly to the host aluminum matrix to yield about a 10% increase in the modules of elasticity of the aluminum lithium alloys produced by the main aluminum producers. The density of the alloys is about 10% less than that of other stmctural aluminum alloys. 

Table 3. Data on chemical diffusion in lithium alloy phases.

In substitutional metallic solid solutions and in liquid alloys the experimental data have been described by Epstein and Paskin (1967) in terms of a predominant frictional force which leads to the accumulation of one species towards the anode. The relative movement of metallic ion cores in an alloy phase is related to the scattering cross-section for the conduction electrons, which in turn can be correlated with the relative resistance of the pure metals. Thus iron, which has a higher specific resistance than copper, will accumulate towards the anode in a Cu-Fe alloy. Similarly in a germanium-lithium alloy, the solute lithium atoms accumulate towards the cathode. In liquid alloys the same qualitative effect is observed, thus magnesium accumulates near the cathode in solution in bismuth, while uranium, which is in a higher Group of the Periodic Table than bismuth, accumulated near the anode in the same solvent. 

Aluminum-copper-lithium alloys, 2 321 equilibrium and metastable phases, 2 322t S-Aluminum-copper-magnesium alloy, 2 318-320... 

Aluminum-lead alloys, 2 314 phase transitions, 2 308t Aluminum-lithium alloys, 2 312, 313 15 134-135... 

Bodak, O.I., J. Deberitz, R. Ferro, M. Harmelin, H.L. Lukas, VV Pavlyuk, P. Rogl, R. Smidt-Fetzer and J.K. Schuster, 1995, Evaluated constimtional data, phase diagrams, crystal structures and applications of lithium alloy systems, in Ternary Alloys, eds G. Effenberg, F. Aldinger and O.L Bodak, Vol. 14-15 (MSI, VCH Verlagsgesellschaft). 

Although the electrochemical capacities of lithium alloys may be very large compared to that of carbon (for example, LiAl and Li Sn = 990 mAh/g), the large volume expansion due to the existence of two phases domains results... 

Although lithium is highly reactive, addition of up to 3% Li to aluminum shifts the pitting potential of the solid solution otdy slightly in the anode cUrection in 3.5% NaQ solution (Ref 25). In an extensive corrosion investigation of several binary and ternary aluminum-lithium alloys, modifications to the microstructure that promote formation of the 5 phase (AlLi) were found to reduce the corrosion resistance of the alloy in 3.5%... 

In this chapter studies of physical effects within the elastic deformation range were extended into stress regions where there are substantial contributions to physical processes from both elastic and inelastic deformation. Those studies include the piezoelectric responses of the piezoelectric crystals, quartz and lithium niobate, similar work on the piezoelectric polymer PVDF, ferroelectric solids, and ferromagnetic alloys which exhibit second- and first-order phase transformations. The resistance of metals has been investigated along with the distinctive shock phenomenon, shock-induced polarization. 

This thermodynamically based methodology provides predictions of the lithium capacities in addition to the electrode potentials of the various three-phase equilibria under conditions of complete equilibrium. This information is included as the last column in Table 2, in terms of the number of moles of lithium per kilogram total alloy weight. 

Because of the interest in its use in elevated-temperature molten salt electrolyte batteries, one of the first binary alloy systems studied in detail was the lithium-aluminium system. As shown in Fig. 1, the potential-composition behavior shows a long plateau between the lithium-saturated terminal solid solution and the intermediate P phase "LiAl", and a shorter one between the composition limits of the P and y phases, as well as composition-dependent values in the single-phase regions [35], This is as expected for a binary system with complete equilibrium. The potential of the first plateau varies linearly with temperature, as shown in Fig. 2. 

Numerous compounds are observed in the Li-Ag phase diagram. The alloys are heated under Ar and cast in mild steel crucibles for metallographic examination, with homogeneity achieved by remelting under vacuum. Similar procedures were employed in an earlier study, except that H2 was used in place of Ar. An Ar cover gas was also employed to prepare the brasslike yj phase in the Li-Ag system for structural study. The silver and lithium were melted together in an iron crucible for 15-30 s before cooling without quenching to minimize the loss of lithium-. ... 

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