Ab initio investigations of the durability of iron alloys and titanium

Abstract

In this ab initio work the oxidation of Fe-Cr, Fe-Al, Fe-Cr-V and Fe-Cr-Al, and the elasticity of Fe-Cr-Al alloys and titanium were investigated. The computational method used was Exact Muffin-tin Orbitals method (EMTO). Oxidation was modelled with thermodynamic simulations of the surface composition of the investigated alloy. The elasticity of titanium and Fe-Cr-Al alloy and also the ductility of the Fe-Cr-Al alloy was simulated by calculating the total energies for deformed structures.

Corrosion resistance of iron alloys is based on the formation of the protective layers on the surface of the alloy. The addition of vanadium in Fe-Cr alloy was computationally predicted to improve the formation of the protective scales. The addition of Al increases the corrosion resistance of pure iron but impairs the mechanical properties. On the other hand, a suitable third alloying element improves the corrosion resistance. The concentration boundaries for corrosion resistance and also for ductility for Fe-Cr-Al alloys were presented. The ductility of Fe-Cr-Al was modelled with elastic constants calculations. Elastic constants calculations were also performed for pure titanium and the results were used to model the mechanical properties of cold rolled titanium.