Heating, lithium alloys

Main uses of lithium alloys. Li additions often change completely the properties of metals to which it is added, for instance hardness of A1 and Pb (addition of Li to Pb results in the formation of Pb solid solution and a eutectic at 15.7 at.% Li with LiPb) and ductility of Mg. Al-alloys can be of great interest in aerospace industry Li (as Be) simultaneously reduces the density of A1 and increases its modulus of elasticity. Each 1 mass% Li up to the solubility limit (4.2 mass%) reduces density by about 3% and increases modulus by 5%. Precipitates homogeneously distributed of spherical LiAl3 in diluted Li-alloys during heat treatment may improve strength. 

Li-Al alloys may be prepared electrochemically, generally by coulo-metric deposition of lithium from a molten salt bath, or pyrometallurgically by heating lithium and aluminium at a temperature above the alloy melting point of 720°C. Practical electrode configurations are constructed by ... 

If the device is not designed to use a heat resistant material, a loss of its functionality during reflow soldering may occur. The lithium alloy may react with the electrolytic solution and other components of the battery to cause abrupt bulging or explosion. Therefore, materials resistant to the reflow temperature must be used for the electrolytic solution, separator, or gasket... 

In these cells readily available substances are used as active materials -molten sodium and sulfur working in contact with a solid electrolyte (sodium beta-aluminate). Sulfur-sodium storage cells show rather large values of specific electrical energy. Their working temperature is 350 C, i.e. before use they must be heated up to this temperature. Storage cells with electrodes from iron sulfide and lithium alloys with a melt of chlorides as electrolyte exhibit similar properties. The working temperature of these cells is about 400°C. 

An electrical collector—of iron or stainless steel foil, located between the heat pellet and the lithium alloy anode pellet. This part is not used with a lithium metal anode assembly, which has an integral metal foil cup. In some cases, especially in longer-life batteries, a second metal foil collector is placed between the FeS2 cathode and the heat pellet to buffer or prevent the cathode from exposure to excessive heat. 

Sxocx. Alloys including tin and some lithium compositions characterizing miscellaneous compositions. Most of the Sxxx alloys are nonheat-treatable, but when used on heat-treatable alloys, they may pick up the alloy constituents and acquire a limited response to heat treatment. 

No fewer than 14 pure metals have densities se4.5 Mg (see Table 10.1). Of these, titanium, aluminium and magnesium are in common use as structural materials. Beryllium is difficult to work and is toxic, but it is used in moderate quantities for heat shields and structural members in rockets. Lithium is used as an alloying element in aluminium to lower its density and save weight on airframes. Yttrium has an excellent set of properties and, although scarce, may eventually find applications in the nuclear-powered aircraft project. But the majority are unsuitable for structural use because they are chemically reactive or have low melting points." ... 

Loop Tests Loop test installations vary widely in size and complexity, but they may be divided into two major categories (c) thermal-convection loops and (b) forced-convection loops. In both types, the liquid medium flows through a continuous loop or harp mounted vertically, one leg being heated whilst the other is cooled to maintain a constant temperature across the system. In the former type, flow is induced by thermal convection, and the flow rate is dependent on the relative heights of the heated and cooled sections, on the temperature gradient and on the physical properties of the liquid. The principle of the thermal convective loop is illustrated in Fig. 19.26. This method was used by De Van and Sessions to study mass transfer of niobium-based alloys in flowing lithium, and by De Van and Jansen to determine the transport rates of nitrogen and carbon between vanadium alloys and stainless steels in liquid sodium. 

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-. ... 

Attempts to follow a published procedure for the preparation of 1,3 -dithiole-2-thione-4,5-dithiolate salts [1], involving reductive coupling of carbon disulfide with alkali metals, have led to violent explosions with potassium metal, but not with sodium [2], However, mixtures of carbon disulfide with potassium-sodium alloy, potassium, sodium, or lithium are capable of detonation by shock, though not by heating. The explosive power decreases in the order given above, and the first mixture is more shock-sensitive than mercury fulminate [3],... 

The collected papers of a symposium at Dallas, April 1956, cover all aspects of the handling, use and hazards of lithium, sodium, potassium, their alloys, oxides and hydrides, in 19 chapters [1], Interaction of all 5 alkali metals with water under various circumstances has been discussed comparatively [2], In a monograph covering properties, preparation, handling and applications of the enhanced reactivity of metals dispersed finely in hydrocarbon diluents, the hazardous nature of potassium dispersions, and especially of rubidium and caesium dispersions is stressed [3], Alkaline-earth metal dispersions are of relatively low hazard. Safety practices for small-scale storage, handling, heating and reactions of lithium potassium and sodium with water are reviewed [4],... 

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