Magnetism-Structure Correlations during the epsilon ->tau Transformation in Rapidly-Solidified MnAl Nanostructured Alloys

Journal Article · Tue Jan 21 00:00:00 EST 2014 · Metals

DOI:https://doi.org/10.3390/met4010008· OSTI ID:1211517

Jimenez-Villacorta, F; Marion, JL; Oldham, JT; Daniil, M; Willard, MA; Lewis, LH

Magnetic and structural aspects of the annealing-induced transformation of rapidly-solidified Mn55Al45 ribbons from the as-quenched metastable antiferromagnetic (AF) epsilon-phase to the target ferromagnetic (FM) L1(0) tau-phase are investigated. The as-solidified material exhibits a majority hexagonal epsilon-MnAl phase revealing a large exchange bias shift below a magnetic blocking temperature T-B similar to 95 K (H-ex similar to 13 kOe at 10 K), ascribed to the presence of compositional fluctuations in this antiferromagnetic phase. Heat treatment at a relatively low annealing temperature T-anneal approximate to 568 K (295 degrees C) promotes the nucleation of the metastable L1(0) tau-MnAl phase at the expense of the parent epsilon-phase, donating an increasingly hard ferromagnetic character. The onset of the epsilon ->tau transformation occurs at a temperature that is similar to 100 K lower than that reported in the literature, highlighting the benefits of applying rapid solidification for synthesis of the rapidly-solidified parent alloy.

• Sponsoring Organization: USDOE Advanced Research Projects Agency - Energy (ARPA-E)
• DOE Contract Number: DE-AR0000186
• OSTI ID: 1211517
• Journal Information: Metals, Vol. 4, Issue 1; ISSN 2075-4701
• Country of Publication: United States
• Language: English