Effect of temperature on the elastic anisotropy of pure Fe and Fe0.9Cr0.1 random alloy.

The elastic properties of pure iron and substitutionally disordered 10 at. % Cr Fe-Cr alloy are investigated as a function of temperature by using first-principles electronic-structure calculations by the exact muffin-tin orbitals method. The temperature effects on the elastic properties are included via the electronic, magnetic, and lattice expansion contributions. We show that the degree of magnetic order in both pure iron and Fe(90)Cr(10) alloy mainly determines the dramatic change of the elastic anisotropy of these materials at elevated temperatures. The effect of lattice expansion is found to be secondary but also very important for quantitative modeling.