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 ~3 µm by low-energy ball milling. These MnBi powders were aligned in an 18 kOe field and warm compacted into a bulk magnet at 300 °C for 30 min. The magnet had a density of 8.2 g/cm3 and magnetic properties of Ms = 6.7 kG, Mr = 5.3 kGs, i Hc = 5 kOe, and (BH)max = 6.1 MGOe
Revised: November 2, 2015 |
Published: December 1, 2014
Citation
Nguyen V.V., N. Poudyal, X. Liu, J. Liu, K. Sun, M.J. Kramer, and J. Cui. 2014.High-Performance MnBi Alloy Prepared Using Profiled Heat Treatment.IEEE Transactions on Magnetics 50, no. 12:Article No. 2105506.PNNL-SA-110266.doi:10.1109/tmag.2014.2341659