The effect of Al content on the structural, mechanical, and thermal properties of B2-FeAl and D03-Fe3Al from atomistic study

We investigate the lattice constant, formation enthalpy, elastic constants, bulk modulus, shear modulus, Young's modulus, specific heat, thermal expansion coefficient and microhardness as a function of Al content for B2-FeAl and D03-Fe3Al using static and dynamics simulations with a long-range analytical embedded atom method (la-EAM). The lattice constants of both B2-FeAl and D03-Fe3Al crystals increase with Al content, opposite to the elastic constants, bulk modulus and shear modulus. Stoichiometric B2-FeAl has the lowest formation enthalpy and Young's modulus. The calculation results of Gibbs free energies show that the phase transformation temperature from D03 to B2 decreases with Al content, which is in good agreement with experiments. The microhardness resulting from vacancies for B2-FeAl increases monotonically with Al content, indicating that the resultant microhardness is controlled by the vacancies, which agrees well with experiments.