ROLE OF SI CONCENTRATION ON THE MAGNETIC AND MECHANICAL-BEHAVIOR OF RAPIDLY SOLIDIFIED FE-SI LAMINATIONS

The magnetic and mechanical properties of rapidly solidified Fe-Si lam inations have been investigated as a function of Si concentration in t he range 3 wt% - 7.8 wt%. Magnetic: loss (d.c. - 10 kHz) and tensile s tress-strain experiments, carried out as a function of grain size, put in evidence the magnetic softening and the mechanical hardening follo wing the increase of the Si concentration. In particular, when the con centration c(Si) = 6.7 wt% is attained, the total loss passes, at all frequencies, through a minimum value, which correlates with the vanish ing of the magnetostriction constant. At the same time, mechanical har dening occurs, with monotonical increase of yield stress and work hard ening rate with c(Si). The magnetic analysis, while showing, on the on e hand, a direct link between coercivity and magnetostriction, puts in evidence the relationship existing between the hysteresis and the exc ess loss components and leads to a quantitative assessment of the over all energy loss dependence on the Si content. A Hall-Petch law ibr the yield stress and the fracture stress vs. grain size is verified at al l compositions. This permits one, in particular, to single out a direc t contribution to material hardening coming from phase ordering when c (Si) > similar to 4 wt %.