“…It has been found that in Cu 3 Au [39] and Cu 3 Pt [40], the activation energy of the ordering process is fitted well with the activation energy for the migration of vacancy. It has been shown that DO 22 structure can change to L1 2 structure by simple changes in the location of atoms; so, this is a preferential ordering mechanism, which changes in order in DO 22 to that in L1 2 and because of changes in order, the structural symmetry changes from DO 22 to L1 2 .…”