Alkaline earth metal alloys

As sodium can be used to eliminate impurities contained in metals, one could consider it as a means for producing wanted compounds and alloys. This field of application is rather large and the following cases of alloy production, mainly based on the strong halogen affinity of this metal, may be examined alkaline earth metal alloys, calcium sodium alloys and calcium metal derived from them, and sodium alloys, especially those with potassium, when calcium, magnesium, cerium, aluminum, uranium, thorium, and titanium, for instance, are introduced into a base metal. 

Alkali metal alloys and alkaline earth metal alloys have a wide range of applications. The degree to which the alloys retain the pyrophoric or water-reactive properties of their parent metals depends on their concentration in the alloy, the modifying nature of the alloyed components, and the state of subdivision. Many commercial alloys of this type, present no hazard. Others, such as the potassium-sodium alloys used in heat exchangers, present significant concern. Other alkali and alkaline earth metal alloys include... 

Oxygen Acetaldehyde, acetone, alcohols, alkali metals, alkaline earth metals, Al-Ti alloys, ether, carbon disulflde, halocarbons, hydrocarbons, metal hydrides, 1,3,5-trioxane... 

Rubidium metal alloys with the other alkaU metals, the alkaline-earth metals, antimony, bismuth, gold, and mercury. Rubidium forms double haUde salts with antimony, bismuth, cadmium, cobalt, copper, iron, lead, manganese, mercury, nickel, thorium, and 2iac. These complexes are generally water iasoluble and not hygroscopic. The soluble mbidium compounds are acetate, bromide, carbonate, chloride, chromate, fluoride, formate, hydroxide, iodide. 

Sodium—lead alloys that contain other metals, eg, the alkaline-earth metals, are hard even at high temperatures, and are thus suitable as beating metals. Tempered lead, for example, is a beating alloy that contains 1.3 wt % sodium, 0.12 wt % antimony, 0.08 wt % tin, and the remainder lead. The German BahnmetaH, which was used ia axle beatings on railroad engines and cars, contains 0.6 wt % sodium, 0.04 wt % lithium, 0.6 wt % calcium, and the remainder lead, and has a Brinell hardness of 34 (see Bearing MATERIALS). 

Leicht-metall, n. light metal (of sp. gr. less than 5 sometimes, specif., an alkali or alkaline-earth metal) light alloy, -dl, n. light oil. leicht-schmelzbar, a. easily fusible, -schmel-zend, -schmelzlich, a. low-melting, -siedend a. low-boiling. 

A mercury cathode finds widespread application for separations by constant current electrolysis. The most important use is the separation of the alkali and alkaline-earth metals, Al, Be, Mg, Ta, V, Zr, W, U, and the lanthanides from such elements as Fe, Cr, Ni, Co, Zn, Mo, Cd, Cu, Sn, Bi, Ag, Ge, Pd, Pt, Au, Rh, Ir, and Tl, which can, under suitable conditions, be deposited on a mercury cathode. The method is therefore of particular value for the determination of Al, etc., in steels and alloys it is also applied in the separation of iron from such elements as titanium, vanadium, and uranium. In an uncontrolled constant-current electrolysis in an acid medium the cathode potential is limited by the potential at which hydrogen ion is reduced the overpotential of hydrogen on mercury is high (about 0.8 volt), and consequently more metals are deposited from an acid solution at a mercury cathode than with a platinum cathode.10... 

Diffusion coefficients in amorphous solids such as oxide glasses and glasslike amorphous metals can be measured using any of the methods applicable to crystals. In this way it is possible to obtain the diffusion coefficients of, say, alkah and alkaline earth metals in silicate glasses or the diffusion of metal impurities in amorphous alloys. Unlike diffusion in crystals, diffusion coefficients in amorphous solids tend to alter over time, due to relaxation of the amorphous state at the temperature of the diffusion experiment. 

Up till now anionic mercury clusters have only existed as clearly separable structural units in alloys obtained by highly exothermic reactions between electropositive metals (preferably alkali and alkaline earth metals) and mercury. There is, however, weak evidence that some of the clusters might exist as intermediate species in liquid ammonia [13]. Cationic mercury clusters on the other hand are exclusively synthesized and crystallized by solvent reactions. Figure 2.4-2 gives an overview of the shapes of small monomeric and oligomeric anionic mercury clusters found in alkali and alkaline earth amalgams in comparison with a selection of cationic clusters. For isolated single mercury anions and extended network structures of mercury see Section 2.4.2.4. 

General characteristics of alloys such as those presented in Fig. 3.3 have been discussed by Fassler and Hoffmann (1999) in a paper dedicated to valence compounds at the border of intermetallics (alkali and alkaline earth metal stannides and plumbides) . Examples showing gradual transition from valence compounds to intermetallic phases and new possibilities for structural mechanisms and bonding for Sn and Pb have been discussed. Structural relationships with Zintl phases (see Chapter 4) containing discrete and linked polyhedra have been considered. See 3.12 for a few remarks on the relationships between liquid and amorphous glassy alloys. 

Figure 4.17. The binary phase diagrams of the magnesium alloy systems with the divalent metals ytterbium and calcium (Ca is a typical alkaline earth metal and Yb one of the divalent lanthanides). Notice, for this pair of metals, the close similarity of their alloy systems with Mg. The compounds YbMg2 and CaMg2 are isostructural, hexagonal hP12-MgZn2 type.

ALLOYS OF THE ALKALINE EARTH METALS AND OF THE DIVALENT RARE EARTH METALS... 

The 3rd group metals a summary of their atomic and physical properties 5.5.5.1 The rare earth metals. A summary of the main atomic and physical properties of the rare earth metals has been collected in Tables 5.11-5.13. To complete the information and the presentation of the entire series of lanthanides the data relevant to Eu and Yb have been included in these tables. However, the same data are reported also in Table 5.7 in comparison with those of the other typical divalent metals (the alkaline earth metals). As for the properties of liquid rare earth metals and alloys see Van Zytveld (1989). 

Figure 5.14. Compound formation capability in the binary alloys of Sc, Y, light trivalent lanthanides (as exemplified by La), heavy trivalent lanthanides (exemplified by Gd) and of the actinides (exemplified by Th, U and Pu). The different partners of the 3rd group metals are identified by their position in the Periodic Table. Notice that a sharper subdivision between compound-forming and not forming metals will result from a shifting of Be and Mg from their position in the 2nd group towards the 12th group (see 5.12.3). The behaviour of the divalent lanthanides Eu and Yb is shown in Fig. 5.7 where it is compared with that of the alkaline earth metals.

Metals which have been used (generally in inert or reducing atmosphere) as container materials are W (melting point 3422°C), Mo (2623°C), Pt (1769°C), Fe (1538°C), Ni (1455°C), Cu (1085°C), Au (1064°C), Ag (962°C). W and Mo do not react with many elements they must be protected however from air oxidation. Pt and Au cannot be used, owing to their reactivity, for melting metallic materials they are useful for other types of synthesis. Fe, of very high purity and with very low carbon content, could possibly be used for melting alkaline and alkaline earth metals and a number of their alloys. 

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