Binary alloys compound formation capability

Figure 2.22. Compound formation capability in binary systems. The different element combinations are mapped on Mendeleev number coordinates and those systems are indicated in which the formation of intermediate phases has been observed (either from the liquid or in the solid state). Blank boxes indicate systems for which no certain data are available. Notice that the compound-forming alloys are crowded in a region corresponding to a large difference in the Mendeleev numbers of the elements involved (for instance, basic metals with semi-metals).

Figure 5.6. Compound formation capability in the binary alloys of alkali metals. The different elements, the binary combinations of which with Li, Na, K, Rb, Cs are considered, are identified by their positions in the Periodic Table. No rehable data have been found about the stable equilibrium phases in the Na-P and Cs-As systems compound formation is, however, probable.

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.

Figure 5.17. Compound formation capability in the binary alloys of Ti, Zr, Hf. Notice the reactivity pattern similar to that shown by the metals of previous groups. No compound formation with metals of the first groups, except Be, lanthanides included.

Figure 5.20. Compound formation capability in the binary alloys of V, Nb, Ta.

Figure 5.33. Compound formation capability in the binary alloys of Be, Mg, Zn, Cd, Hg. For a comparison A1 and Ca patterns are also shown.

In the conclusion of this chapter and on the basis of the data and schemes shown in the preceding paragraphs, we summarize some regularities observed in the description of the alloying behaviour shown by the different binary alloys. Giving special attention to the compound formation capability, the following points, even though qualitative, are underlined ... 

Trends in the formation capability of binary compounds. A few general comments about the formation of intermediate phases in binary alloy systems can be made by using maps similar to those previously employed in Fig. 2.8 in order to give a summary of the mutual solubility. 

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