Structural stability and magnetic properties of metastable Fe-Cu alloys studied by ab initio calculations and molecular dynamics simulations -: art. no. 054203

For the equilibrium immiscible Fe-Cu system, ab initio calculations using the projector augmented wave method identify the relatively stable structures of the metastable Fe25Cu75 and Fe50Cu50 alloys to be both of fcc and determine their corresponding lattice constants and cohesive energies. Some of the ab initio calculated properties are used in deriving an embedded-atom Fe-Cu potential. Based on the proven realistic potential, the structural stability of the FexCu100-x alloy is studied for the entire composition range of the system through molecular dynamics simulations. The simulations predict that a fcc structure is more stable than a bcc one when 0less than or equal toxless than or equal to60, while the bcc structure becomes energetically favored when 60<xless than or equal to100, and that the prediction confirms the verdict from ab initio calculations for the Fe25Cu75, Fe50Cu50, and Fe75Cu25 alloys. Moreover, ab initio calculations are also performed to determine the magnetic moments of some metastable Fe-Cu alloys and the results are reasonably compatible with the experimental observations.