Keywords
Abstract
In the framework of the density functional theory, the alloying effect of Si on the magnetic and elastic properties, as well as the thermodynamic stability at T = 0 K of ferromagnetic Fe-Cr solid solutions in the BCC structure was studied. Calculations of lattice parameters, mixing enthalpy, elastic constants, bulk moduli, Young’s and shear moduli of disordered binary Fe-Cr and triple Fe-Cr-Si alloys containing 2.3 at. % and 4.7 at. % Si were performed using PAW-SQS and EMTO-CPA methods. Effective chemical interactions of the configuration Hamiltonian, magnetic characteristics and exchange interactions of the Heisenberg Hamiltonian are obtained. A comparative analysis of all obtained properties for ternary Fe-Cr-Si alloys with respect to binary Fe-Cr alloys is carried out. It was found that the addition of 2.3 at. % Si increases the thermodynamic stability of Fe-Cr alloys; this effect is enhanced with an increase in the silicon concentration to 4.7 at.%. The result is due to the Fe-Si and Cr-Si chemical interactions in addition to the magnetic Fe-Cr interactions that determine the stability of the diluted binary alloys. It is shown that with Si addition an increase in the elastic constant C44 is observed, the values of the constants C11, C12 and elastic moduli are close to the corresponding values of binary Fe- Cr alloys. Analysis of the concentration dependence of the ductility parameter G/B and charge density difference maps allowed to establish correlations between the changes in interatomic bonding and the properties of the alloys.