Examination of second order elastic constants for Fe-Al alloys

The stability criteria developed by Max BORN have been applied to the study of the second order elastic constants for Fe(1-x)-Al(x)(x=0.00, x=0.25, x=0.30) in bcc, disorder and DO3 phases, respectively. For the interactions between the atoms, the generalised Morse and Modified Morse potential energy functions have been used separately. These functions are given below:Therefore, these pair interatomic potentials have been tested for the second order elastic constants for Fe(1-x)-Al(x) systems. Second order elastic constants in the direction of one axis, have been also calculated. Finally, the equilibrium conditions have been determined from the computed numerical values. While the modified Morse potential don?t satisfy the stability criteria, it is seen that Morse potential defined for m=2 satisfies the BORN criteria.Key Words: Elastic Constants, Two-Body İnteractions, Mechanical Stability, Stres.