Long-range atomic order and grain boundary ensemble in alloys with L12 superstructure

Abstract

It is found experimentally that in the Ni₃Mn and Pd₃Fe alloys with superstructure L1₂, ordered through a two-phase region A1 + L1₂, an increase in the degree of long range atomic order is accompanied by a reduction in the special and twin boundaries’ angle of deviation from the special boundaries in the CSL model, and by a change in the special boundaries’ spectrum and its average energy. The dependence of the proportion of Σ3 twin boundaries within the spectrum of special boundaries and the average energy of special boundaries on the degree of long range atomic order is determined by the dependence of these parameters on the mean square displacement and probability of antiphase grain boundaries being superimposed on the boundary planes, and on the presence of second phases on special boundaries.