Institute of Quantum Materials Science, IQMS

Solubility of alloying elements in bcc and fcc Fe

O.I.Gorbatov, I.K. Razumov, Yu N Gornostyrev

The solution enthalpy of alloying elements in bcc and fcc Fe has been calculated by using of the density functional theory methods implemented in CPA-KKR-GF approach. It is shown that transition to the paramagnetic state with increase of temperature results in higher solution enthalpy for the elements on the left side from iron (Ti, V, Cr, Nb, Mo). Copper is one alloying element that solution enthalpy is positive for all structural and magnetic states of Fe and go down when temperature increase.

Fig.1. The solution enthalpy of alloying elements in dependence on position in Periodic Table in bcc Fe feppromagnetic (●), paramagnetic (▲)states and in paramagnetic fcc Fe (□). The results of first principles calculations by CPA-KKR-GF method.

 

The features of decomposition kinetics and morphology of precipitates in iron based binary and ternary systems have been investigated vy Monte-Carlo modeling with a-initio effective cluster interactions for ferromagnetic and paramagnetic states within wide concentration and temperature domains. We found that magnetic state of iron is important factor which determined the interactions between solute atoms early decomposition stage. This approach allows to predict the solubility limits and the condition of the formation nano-precipitates.

Fig.2. The energy of effective pair Cu-Cu interactions in bcc Fe for different magnetic states (left) and solubility limit of Cu in dependence on temperature (right), obtained by Monte-Carlo modeling with first principle parameterization (◊) in comparison with experiment (●).