Ordering phenomena in Fe-Si alloys with variable Si-content (0.2-11.7 wt.%) and thermomechanical processing

Abstract

Fe-Si electrical steel around 6.5 wt. % Si is an optimum material for soft magnetic applications. Nevertheless, the brittleness appearing above 3.5 wt. % Si makes the cold processing very difficult to carry out. It is generally believed that the embrittlement is caused by order/disorder phenomena. Mössbauer spectroscopy was used to investigate the ordering processes in several Fe-Si-alloys with up to 11.7 wt. % Si. Type and degree of ordering were determined and results show that the alloys are never random solid solutions and their order degree increases with the silicon content. In addition, the effect of the thermomechanical processing was analysed. It is shown that slow cooling promotes B2 ordering while fast cooling does the opposite. On the other hand, cold rolling tends to cause disordering on the alloys.