Alignment of two-phase structures in Fe-C alloys by application of magnetic field

Application of magnetic fields up to 12 T during the alpha --> gamma invers e transformation in Fe-0.1 mass%C and Fe-0.6 mass%C alloys was found to yie ld two-phase microstructures with the paramagnetic gamma phase aligned as c hains or columns along Ulf direction of the applied magnetic field in the m atrix of the ferromagnetic alpha phase. The alignment was found to be indep endent of the rolling directions during the preparation of specimens. Furth er, it was unrelated to the microstructure of the prior gamma phase. This p henomenon is explained by a model or the coalescence and growth of the nucl ei of the inverse gamma phase under the dipolar interactions in the backgro und of the ferromagnetic alpha phase. The applied magnetic field raises the inverse transformation temperature by 1 degrees C/T in accordance to the m agnetic free energy change.