First-principles study on the dilute Si in bcc Fe: Electronic and elastic properties up to 12.5 at.%Si

In order to understand the effect of Si on various properties in bcc Fe, first-principles calculations are employed to investigate the elastic, electronic, and bond characteristic of Fe–Si system with the main focus on dilute Si up to 12.5 at.%Si concentrations based on electronic structure calculations. The stress–strain method for elasticity are performed to obtain the elastic constants of dilute Si in bcc Fe at 0, 2.4, 5.6, 8.3, 10.9, and 12.5 at.%Si. The calculated elastic properties show significantly change beyond 8.3 at.%Si. The bulk to shear modulus ratio indicate the ductile to brittle transition as the Si content increases beyond 8.3 at.%. Electronic density of states, local magnetic moment, and force constants results indicate different Fe–Si bond characteristic between above and below 8.3 at.%Si concentrations which can be taken as the combined effect of the magnetic property and the ordering tendency from bcc solid solution to partial ordering of D03 around 10.9 at.%Si.