Effects of adding Cu on the microstructure and properties of in-situ alloyed Fe–Cr–Co permanent magnets by laser powder bed fusion

In this paper, high-density (60−x)Fe−Cr−Co−xCu (x: 0–6 wt.%) permanent magnet alloys were fabricated by laser powder bed fusion (LPBF) in-situ alloying technique, and the effects of Cu content on the microstructure, magnetic, and mechanical properties of the alloy were systematically investigated. The addition of 2 wt.% Cu enhanced the coercivity \({H}_{c}\) $H_c$ and the energy product \({(BH)}_{max}\) ${(BH)}_{\mathit{max}}$ of the alloy in the isotropic state by 19.4 and 27.9%, respectively, compared to the alloy without Cu. The impacts of Cu content on the magnetic properties were investigated by combining experimental results and first-principles calculations. Furthermore, the addition of Cu improved the yield strength of the alloy, and the strengthening mechanism was analyzed in detail. The yield strength of the alloy with 2 wt.% Cu reached 908 MPa, representing a notable 7% increase relative to the Cu-free alloy.