Correlation between electronic structure, magnetism and physical properties of Fe-Cr
alloys: ab initio modeling
I. A. Abrikosov
Department of Physics, Chemistry and Biology, Linköping University, Sweden
We review recent developments in the field of ab initio electronic structure theory and its
application for studies of complex alloy systems. Basic ideas behind state-of-the-art
techniques for first-principles theoretical simulations of the phase stabilities and
properties of intermetallic compounds and alloys based on the density functional theory
are outlined. We concentrate on methods that allow for an efficient treatment of disorder
effects [1,2], and illustrate their predictive power for the case of Fe-Cr system.
In the binary Fe-Cr alloy the decomposition occurs either via the nucleation and growth
mechanism or as spinodal decomposition, depending on the Cr content. However, at low
chromium concentrations the alloys are anomalously stable. This is shown to be true only
for the ferromagnetic body centered cubic (bcc) phase[3,4]. Indeed, we show that in the
paramagnetic alloys the concentration dependencies of the thermodynamic properties are
smooth functions of alloy concentration, in agreement with the high-temperature
experiment. However, in the ferromagnetic case there are peculiarities of the mixing
enthalpy and bulk moduli in the low-Cr region in the bcc phase. We show that the
stability of the low-Cr steels stems from the negative mixing enthalpy at low
concentrations of chromium. We explain the effect by variations of the electronic
structure in the alloy with concentration. Consequences of the strong concentration
dependence of the interatomic interactions in Fe-Cr system are discussed.
[1] I. A. Abrikosov, A. M. N. Niklasson, S. I. Simak, B. Johansson, A. V. Ruban, and
H. L. Skriver, Phys. Rev. Lett. 76, 4203 (1996).
[2] L. Vitos, I. A. Abrikosov, and B. Johansson, Phys. Rev. Lett. 87, 156401 (2001).
[3] P. Olsson, I. A. Abrikosov, L. Vitos, and J. Wallenius, J. Nucl. Mat. 321, 84 (2003).
[4] P. Olsson, I. A. Abrikosov, and J. Wallenius, Phys. Rev. B 73, 104416 (2006).