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We report on improved high-temperature soft magnetic properties in Fe88−2xCoxNixZr7B4Cu1 nanocrystalline alloys. Substituting 5.5 at. % Co and Ni for Fe enhances the magnetization by 5% at ambient temperature and by 30% at 650 °C. The Curie temperature of the residual amorphous phase is also raised significantly (from 67 °C for x=0 to 298 °C for x=5.5), resulting in low coercivities (<30 A m−1) for Fe77Co5.5Ni5.5Zr7B4Cu1 over the temperature range 50–500 °C. The higher magnetization and Curie temperature as compared with other Fe-based alloys, and smaller Co content as compared with (Fe,Co)-based alloys, make this alloy attractive as an affordable high-temperature soft magnetic material.

In this letter, we report on the achievement of exchange anisotropy magnitude in a nanostructured Mn55Al45 alloy fabricated by rapid solidification with large exchange bias values (HE ≈ 13 kOe at 10 K) and a blocking temperature of TB ∼ 95 K. Field-cooled magnetization loops show a prominent exchange bias for T < TB signaling the simultaneous presence of antiferromagnetic and ferromagnetic phases at these temperatures. Structural probes confirm a majority presence of the high-temperature metastable hexagonal ɛ-MnAl in the as-solidified state with an intriguing double-Bragg peak structure indicative of phase separation. The observed exchange bias is hypothesized to originate from an intimate mixture of antiferromagnetic and nanoscaled ferromagnetic phases or dual mictomagnetic phases, approximating a cluster glass with well-defined variations in the local Mn concentration of the composition and leading to Mn-rich and Mn-poor regions with antiferromagnetic and ferromagnetic characters, respectively.

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