A low coercivity, high Si content, directed energy deposited Fe-6%Si electrical steel

Increasing the Si content in Fe-Si alloys increases the resistivity and decreases eddy current losses. While conventional processing of high Si content Fe-Si alloys is challenging, additive manufacturing has been demonstrated as a viable alternative. However, it has been quite challenging to understand the nature of chemical ordering (B2/D0₃ type) in these AM processed alloys, and its consequent influence on the coercivity (H_c) and saturation magnetization (M_s). Hence, in this work, a Fe-6 wt% Si alloy was prepared by laser directed energy deposition (DED) using different laser fluences (energy densities). The presence of body centered cubic (BCC) grains with B2 and D0₃ type chemical ordering in the as-deposited condition, was conclusively established by coupling synchrotron-based x-ray diffraction and transmission electron microscopy investigations. While laser fluence significantly influenced BCC grain size and texture, the resulting alloy exhibited exceptional soft magnetic properties, achieving a M_s value of 201 emu/g and a low H_c of 1.1 Oe. Post-deposition heat treatment further reduced the H_c value to ∼0.8 Oe, rendering this DED processed Fe-6wt% Si alloy highly suitable for engineering applications.