It is well established that dipolar interactions in colloidal magnetic fluids are the
mechanism of the pattern formation
such as chains or columns. We report the first observation of structure formation in
steels exposed to a magnetic field.
A magnetic field higher than 2T is found to align the microstructure of steels parallel
to the field during the
transformation from the paramagnetic fcc phase to the ferromagnetic bcc phase and
vice versa. Evidence is presented
for the dipolar interactions between the ellipsoidal nuclei in the background of the
matrix with a different magnetic
character. Electron back scattering diffraction has revealed that the transforming
nuclei in a magnetic field are at
random in their crystallographic orientation. r 2002 Elsevier Science B.V. All rights
reserved.
