Mechanical stability of Fe (1-x)-AL (x) (x-0.0, 0.25, 0.30)

MECANİCAL STABILITY OF Fe (i.x)-AI(x) (x = 0.0, 0.25, 0.30) SYSTEMS (M.Sc. Thesis) Hamza Yaşar OCAK GAZİ UNIVERSITY INSTUTE OF SCIENCE AND TECHANOLOGY FEBRUARY 1995 ABSTRACT The stability criteria developed by Max BORN have been applied to the study of the mechanical stability forFe (]_xy-Al(x) systems (x = 0.0, 0.25, 0.30) in bcc, disorder and D03 phases, respectively. For the interactions between the atoms, the generalised Morse and Modified Morse potential energy functions given below have been used separately. D *M = (^i) -ma(rrr0) _ -a(rj-r0) *W D (m-1) -ma(rj-r0) -a(rrr0) e - me Therefore, these pair interatomic potentials have been tested for the mechanical stability for Fe (i_xy-Al(x) systems. For the cristal lattices the potential parameters have been computed using Akgiin model and Girifalco-Weizer method. Energies, energy densities, elastic constants and stresses of these systems which deformed homogeneously by a force acting 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 the Morse potential defined for m=2 satisfies the BORN criteria. Science Code Key Words Page number Adviser :4040501 :Two-body inleractions,energy, stress, densty of energy, elastic constants and mechanical stability :86 : Doç. Dr. İrfan AKGÜN rr