A phase field study for influence of elastic energy on L10→L12 transient ordering in Ni75Al17Zn8

The influence of the elastic energy on L1(0)-> L1(2) transient ordering transformation was investigated by microscopic phase field method. It is found that there are three stages experienced in atomic ordering: solute clustering+L1(0) short range ordering -> L1(0) long range ordering -> L1(2) long range ordering. Before the formation of the high ordered L1(2) phase, it has firstly taken place the transformation from matrix to L1(0) phase, and then held the L1(0)-> L1(2) secondary transformation. Elastic energy is proved to take little effect on the stage of short range ordering, but as the elastic energy is multiplied, it obviously shortened the course of the solute clustering, and speeded up the proceeding of the L10 long range ordering transition. Accordingly, the increased elastic energy also strengthens the single crystalline directionality of L10 phase projecting on 2D plane and makes the ordered degree of Al and Zn atoms enhanced. With the temperature elevation, Al's and Zn's ordered degree decreased in L1(0) phase.