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High-Performance MnBi Alloy Prepared Using Profiled Heat Treatment

TitleHigh-Performance MnBi Alloy Prepared Using Profiled Heat Treatment
Publication TypeJournal Article
Year of Publication2014
AuthorsNguyen, VV, Poudyal, N, Liu, XB, Liu, JP, Sun, KW, Kramer, MJ, Cui, J
JournalIEEE Transactions on Magnetics
Date Published12
Type of ArticleArticle
ISBN Number0018-9464
Accession NumberWOS:000349445500003
Keywordsmagnetic-properties, MnBi, Permanent magnet, phase, profiled heat treatment (PHT)

The profiled heat treatment (PHT) method has been used to synthesize MnBi alloys with high-purity low-temperature phase (LTP). In the PHT method, the arc-melted MnBi alloy was remelted then slowly cooled by a pseudo-equilibrium solidification process to promote the formation of LTP phase. The PHT-treated MnBi alloys had an LTP phase up to 94 wt.% and a magnetization of 73 emu/g under a field of 9 T. Scanning electron microscopy showed that there exist some micrometer-sized Mn-rich inclusions in the LTP matrix of the PHT MnBi alloy. The PHT MnBi alloys were crushed into powders with an average size of similar to 3 mu m by low-energy ball milling. These MnBi powders were aligned in an 18 kOe field and warm compacted into a bulk magnet at 300 degrees C for 30 min. The magnet had a density of 8.2 g/cm(3) and magnetic properties of M-s = 6.7 kG, M-r = 5.3 kGs, (i) H-c = 5 kOe, and (BH)(max) = 6.1 MGOe.

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