Abstract: Magnetic and structural aspects of the annealing-induced transformation of rapidly-solidified Mn55Al45 ribbons from the as-quenched metastable antiferromagnetic (AF) ε-phase to the target ferromagnetic (FM) L10 τ-phase are investigated. The as-solidified material exhibits a majority hexagonal ε-MnAl phase revealing a large exchange bias shift below a magnetic blocking temperature TB~95 K (Hex~13 kOe at 10 K), ascribed to the presence of compositional fluctuations in this antiferromagnetic phase. Heat treatment at a relatively low annealing temperature Tanneal ≈ 568 K (295 °C) promotes the nucleation of the metastable L10 τ-MnAl phase at the expense of the parent ε-phase, donating an increasingly hard ferromagnetic character. The onset of the ε→τ transformation occurs at a temperature that is ~100 K lower than that reported in the literature, highlighting the benefits of applying rapid solidification for synthesis of the rapidly-solidified parent alloy.
Keywords: nanostructured magnetic materials; Mn-based magnets; rapid-solidification
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Jiménez-Villacorta, F.; Marion, J.L.; Oldham, J.T.; Daniil, M.; Willard, M.A.; Lewis, L.H. Magnetism-Structure Correlations during the ε→τ Transformation in Rapidly-Solidified MnAl Nanostructured Alloys. Metals 2014, 4, 8-19.
Jiménez-Villacorta F, Marion JL, Oldham JT, Daniil M, Willard MA, Lewis LH. Magnetism-Structure Correlations during the ε→τ Transformation in Rapidly-Solidified MnAl Nanostructured Alloys. Metals. 2014; 4(1):8-19.
Jiménez-Villacorta, Felix; Marion, Joshua L.; Oldham, John T.; Daniil, Maria.; Willard, Matthew A.; Lewis, Laura H. 2014. "Magnetism-Structure Correlations during the ε→τ Transformation in Rapidly-Solidified MnAl Nanostructured Alloys." Metals 4, no. 1: 8-19.