I. Poschmann et al., SUPERLATTICE DISLOCATIONS AND ANTIPHASE BOUNDARIES IN FE3SI, Philosophical magazine. A. Physics of condensed matter. Defects and mechanical properties, 71(5), 1995, pp. 1083-1107
TEM investigations of D0(3)-ordered Fe3Si reveal dislocations belongin
g to the slip system [100]{001}. The glissile superlattice dislocation
s consist of two superlattice partial dislocations with Burgers vector
b=a(0)/2[100](100) which are linked together by an antiphase (APE(NNN
)) which changes the next nearest neighbour. The dissociation width is
of the order of 100 nm. The TEM observations are analysed by means of
thermodynamics. The state of order of the undisturbed crystal and the
free energy of the APE using the concept of thermodynamic relaxation
of an antiphase boundary are calculated. The behaviour of the APE in t
he vicinity of a phase transition of the first and second kind is stud
ied. It is shown that the APE can be seen as the B2 nucleus during pha
se transition D0(3)-->B2 below the Curie temperature.