Valence electron structure analysis of Mg-Zr alloy solid solution

Based on empirical electron theory of solids and molecules (EET), valence electron structure of Mg-Zr alloy solid solution was analyzed, and the statistical value of shared electron pair number of the strongest covalent bond (n'A), the group number of the possible atom state in cell (σN), the statistical of covalent electron density differences at different types of phase interface (Δ ρ') and the group number of the possible atom state in the phase interface (σ) which characterized the mechanical properties of Mg-Zr alloy were calculated. The results showed that the statistical value of shared electron pair number of the strongest covalent bond (n'AMg-Zr) of Mg-Zr solid solution was 0.12984, which was significantly greater than that of pure Mg (0.10991). Moreover, the corresponding group number of atom state σNMg-Zr (9) > σNMg (1), thus indicating that the solution of Zr element produced a significant solid solution strengthening effect. And the relationship among the statistical value of covalent electron density differences at different types of phase interface in the alloy was that Δ ρ'Mg/Mg-Zr=16.5541>Δ ρ'Mg-Zr/Mg-Zr=3.8673>Δ ρ'Mg/Mg=0, while the corresponding group number of sets of the atom state was as follows: σMg-Zr/Mg-Zr=45>σMg/Mg-Zr=9>σMg/Mg=1; the increase of Δ ρ' value indicated that the addition of alloying elements Zr improved the interface stress and increased the dislocation density; as a result, both of the phase interface and matrix were strengthened; while the increase of σ value indicated that the solution of Zr into matrix promoted the continuity of electron density at the interface of Zr contained unit cell, enhanced the mobility of dislocation, improved the ductility of alloy and reduced the stress corrosion sensitivity. The alloy element Zr increased the value of n'A, Δ ρ' and σ of Mg-Zr alloy, which could be attributed to the solution strengthening and the interface strengthening. © 2015, Editorial Office of Chinese Journal of Rare Metals. All right reserved.