First-principles studies on alloying and simplified thermodynamic aqueous chemical stability of calcium-, zinc-, aluminum-, yttrium- and iron-doped magnesium alloys.

In the present study, the density functional theory implemented in the Vienna Ab-initio Simulation Package has been used to investigate the alloying effects of different elements of calcium, zinc, yttrium, aluminum and iron when introduced in the Mg crystal lattice. In particular, studies have been conducted to investigate the thermodynamics of the overall hydrolysis reaction of the different alloys with pure water. Phase stability results obtained from the first-principles calculations of the alloys considered are in good agreement with the published phase diagrams. The heats of the aqueous chemical reactions calculated in this study have been compared with that corresponding to the reaction of pure Mg with water. The heats of reactions dependence on the chemical compositions of the alloys have been investigated and, specifically, the role of Ca, Zn, Y, Al and Fe on the aqueous chemical stability and reactivity of these Mg alloys have been discussed. Results of these studies will help understand the biodegradable characteristic of Mg based alloys.