Order-disorder transitions in binary alloys with the fcc (100) surface

Abstract

Order-disorder transitions in binary alloys A x B 1-x with the fcc(100) surface have investigated by use of the cluster variation method within a framework of the tetrahedron approximation. According to the theory developed by Sanchez et al, phase diagrams in surfaces composed of the first several layers have been calculated above the bulk transition temperature T B . Taking account of only the nearest neighbor pairwise interactions, we have found successive transitions and a surface re-entrant transition. At T n , only the nth layer orders and other layers remain unchanged. The transition temperature from the disordered phase to the ordered phase is given by the largest value among T n 's.