| Abstract: | The Brewer-Engel theory has previously provided quantitative predictions of thermodynamic properties and crystal structures of metallic systems which have not previously been subject to generalized Lewis acid-base interactions (L. Brewer, in J.L. Walter, M.R. Jackson and C.T. Sims (eds.), Alloying, ASM International, Metals Park, OH, 1988, pp. 20–27; J. Kouvetakis and L. Brewer, J. Phase Equilib., 14 (1993) 563). The theory has now been extended to cover any combination of metals. A modified Born-Haber type cycle has been used to characterize both covalent and ionic bonding. The understanding of chemical bonding provides the means of predicting a variety of properties. Enhancement of d-bonding is obtained by generalized Lewis acid-base interactions between transition metal atoms (L. Brewer, in J.L. Walter, M.R. Jackson and C.T. Sims (eds.), Alloying, ASM International, Metals Park, OH, 1988, pp. 20–27). In contrast, the d-bonding is reduced when non-transition metals are added to transition metals (L. Brewer, J. Phys. Chem., 94 (1990) 1196). This present paper illustrates the calculation procedures for transition metals added to Al and Mg. The calculations are presented for AB alloys which exhibit CsCl structure for composition of 50 at.% A(transition metal) and 50 at.% B(Al or Mg). |
