Ab initio calculations of elastic properties of bcc Fe-Mg and Fe-Cr random alloys

作者：Zhang Hualei^*; Johansson Borje; Vitos Levente

来源：Physical Review B, 2009, 79(22): 224201.

DOI：10.1103/PhysRevB.79.224201

• ab initio calculations
• elastic moduli
• ferromagnetic materials
• iron alloys
• lattice constants
• linear muffin-tin orbital method
• magnesium alloys
• solubility

Using the ab initio exact muffin-tin orbitals method in combination with the coherent-potential approximation, we have calculated the elastic parameters of ferromagnetic Fe(1-m)Mg(m) (0 < m < 0.1) and Fe(1-c)Cr(c) (0 < c < 0.2) random alloys in the body-centered cubic (bcc) crystallographic phase. Results obtained for Fe(1-c)Cr(c) demonstrate that the employed theoretical approach accurately describes the experimentally observed composition dependence of the polycrystalline elastic moduli of Fe-rich alloys encompassing maximum similar to 10% Cr. The elastic parameters of Fe-Cr alloys are found to exhibit anomalous composition dependence around 5% Cr. The immiscibility between Fe and Mg at ambient conditions is well reproduced by the present theory. The calculated lattice parameter for the Fe-Mg regular solid solution increases by similar to 1.95% when 10% Mg is introduced in Fe, which corresponds approximately to 11% decrease in the average alloy density, in perfect agreement with the experimental finding. At the same time, we find that all of the elastic parameters of bcc Fe-Mg alloys decrease almost linearly with increasing Mg content. The present results show a much stronger alloying effect for Mg on the elastic properties of alpha-Fe than that for Cr. Our results call for further experimental studies on the mechanical properties of the Fe-Mg system.

• 出版日期2009-6
• 单位大连理工大学