Influence of Ca addition on valence electron
structure of Mg17Al12
structure of Mg17Al12
(Department of Materials Science and Engineering, Southeast University,
Nanjing 210096, China)
Nanjing 210096, China)
Abstract: The alloy AZ91 containing calcium was prepared under protection of a mixed gas atmosphere of SF↓6 (1%, volume fraction) and CO2. The added calcium mainly dissolves into the Mg17Al12 phase in the alloy and increases its melting point and the thermal stability. The empirical electron theory (EET) of solid and molecules was used to calculate the valence electron structures (VES) of Mg17Al12 phase with different amounts of calcium additions. The theoretical calculations indicate that calcium dissolved in Mg17Al12 phase increases the strengths of atomic bonds that control the thermal stability of Mg17Al12 phase, and also makes the distribution of valence electrons on the dominant bond network as well as in the whole unit cell of Mg17Al12 more uniform, which are consistent with the experimental results.
Key words: magnesium alloy; Mg17Al12; calcium; valence electron structure