Fe–Co-based crystalline soft magnetic coatings with ultra-high saturation magnetization above 1.9T via co-axial powder feeding plasma-transferred arc welding

Abstract

Fe–Co-based soft magnetic alloys (SMAs) have played important roles in vehicle electrification technologies and attracted increasing attentions for their excellent magnetic properties. In the current work, Fe–Co-based crystalline monolayer coatings with ultra-high saturation magnetization (Ms) above 1.9T were facilely fabricated on AISI 1010 substrate, using (Fe_0.8Co_0.2)₈₅B₁₄Si₁ (at%) self-fluxing alloy as feedstock powders of a co-axial powder feeding plasma-transferred arc (PTA) welding. The phase assemblage, microstructure, hardness, and magnetic properties were investigated, and the welding parameters were optimized using orthogonal experiment. The results show that the optimal powder flow rate, welding current, and speed were 24 g/min, 118 A, and 0.13 m/min, respectively. The optimum coating C9 has a eutectic-dendrite composite structure and the sorbite dendritic cores included in network-like (α-Fe+(Fe_1-xCo_x)₂B) eutectics. The body-centered cubic (b.c.c.) α-Fe multielement solid solution causes a high Ms of 1.96 ± 0.004T. While a high coercivity (Hc) of 38.9 ± 0.2Oe and microhardness of 4.58 ± 0.23GPa result from (Fe_1-xCo_x)₂B in eutectics. This work confirms the feasibility and potential of high-Ms soft magnetic coatings fabricated by conventional co-axial powder feeding PTA welding and facilitates their extended applications in some special fields, e.g., manufacturing hard-wearing soft magnetic parts with complex geometry.