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

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.
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Publication Date:
OSTI Identifier:
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Metals; Journal Volume: 4; Journal Issue: 1
Sponsoring Org:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
Country of Publication:
United States