Phase investigations of manganese-bismuth alloyed in a microwave furnace

Abstract

Implementation of manganese-bismuth (MnBi) alloys as high-performance permanent magnets is a challenge for physicists and engineers because the ferromagnetic low-temperature phase (LTP) is not exclusively obtained. In this work, melting powered by four commercial magnetrons of 2000–2500 W in a microwave furnace is demonstrated as a new route to alloy MnBi. Under an argon atmosphere, microwave heating transferred to pieces of broken Bi ingots and Mn flakes for 2 h gave rise to products of inhomogeneous composition and morphology. Scanning electron micrographs were classified into three regions according to morphology and elemental composition. Cubic-like clusters characterized as Mn precipitated over light solidified Bi-rich regions, and the MnBi phase was formed in homogeneous regions with a balanced composition between Mn and Bi. A ferromagnetic hysteresis loop was obtained in the ground powder with a coercivity of 40 kA/m. Subsequent annealing at 553 K under a pressure of 414 kPa for 12 h enhanced the MnBi phase with extended regions of balanced composition. It follows that the coercivity was increased to 60 kA/m. However, remanent magnetization was slightly reduced. This MnBi alloyed by microwave radiation can be further used in rare-earth-free magnets.

Keywords

microwave / manganese / bismuth / scanning electron microscopy / magnetic properties / coercivity

References

[1] PoudyalN, LiuX, WangW, NguyenV V, MaY, GandhaK, ElkinsK, LiuJ P, SunK, KramerM J, CuiJ. Processing of MnBi bulk magnets with enhanced energy product [J]. AIP Advances, 2016, 6: 056004

[2] KimS, MoonH, JungH, KimS M, LeeH S, Choi-YimH, LeeW. Magnetic properties of large-scaled MnBi bulk magnets [J]. Journal of Alloys and Compounds, 2017, 7081245-1249

[3] NguyenV V, NguyenT X. Effect of microstructures on the performance of rare-earth-free MnBi magnetic materials and magnets [J]. Physica B, 2018, 532: 103-107

[4] ParkJ, HongY K, LeeJ, LeeW, KimS G, ChoiC J. Electronic structure and maximum energy product of MnBi [J]. Metals, 2014, 4(3): 455-464

[5] XiangZ, WangT, MaS, QianL, LuoZ, SongY, YangH, LuW. Microstructural evolution and phase transformation kinetics of MnBi alloys [J]. Journal of Alloys and Compounds, 2018, 741: 951-956

[6] CuiJ, KramerM, ZhouL, LiuF, GabayA, HadjipanayisG, BalasubramanianB, SellmyerD. Current progress and future challenges in rare-earth-free permanent magnets [J]. Acta Materialia, 2018, 158: 118-137

[7] JanotovaI, SvecP, SvecP, MatkoI, JanickovicD, KuncaB, MarcinJ, SkorvanekI. Formation of magnetic phases in rapidly quenched Mn-based systems [J]. Journal of Alloys and Compounds, 2018, 749: 128-133

[8] MarkerM C J, TerzieffP, KainzbauerP, BobnarM, RichterK W, IpserH. BiMn: Synthesis, separation by centrifugation, and characterization [J]. Journal of Alloys and Compounds, 2018, 741: 682-688

[9] CuiJ, ChoiJ P, PolikarpovE, BowdenM E, XieW, LiG, NieZ, ZarkevichN, KramerM J, JohnsonD. Effect of composition and heat treatment on MnBi magnetic materials [J]. Acta Materialia, 2014, 79: 374-381

[10] KanariK, SarafidisC, GjokaM, NiarchosD, KalogirouO. Processing of magnetically anisotropic MnBi particles by surfactant assisted ball milling [J]. Journal of Magnetism and Magnetic Materials, 2017, 426: 691-697

[11] LiB, MaY, ShaoB, LiC, ChenD, SunJ, ZhengQ, YinX. Preparation and magnetic properties of anisotropic MnBi powders [J]. Physica B, 2018, 530: 322-326

[12] GabayA M, HadjipanayisG C, CuiJ. Preparation of highly pure a-MnBi phase via melt-spinning [J]. AIP Advances, 2018, 8: 056702

[13] SaitoT, NishimuraR, Nishio-HamaneD. Magnetic properties of Mn-Bi melt-spun ribbons [J]. Journal of Magnetism and Magnetic Materials, 2014, 3499-14

[14] NguyenV V, NguyenT X. An approach for preparing high-performance MnBi alloys and magnets [J]. Journal of Electronic Materials, 2017, 46(6): 3333-3340

[15] XieW, PolikarpovE, ChoiJ P, BowdenM E, SunK, CuiJ. Effect of ball milling and heat treatment process on MnBi powders magnetic properties [J]. Journal of Alloys and Compounds, 2016, 680: 1-5

[16] MiyazakiD, MitsuiY, UmetsuR Y, TakahashiK, UdaS, KoyamaK. Enhancement of the phase formation rate during in-field solid-phase reactive sintering of Mn-Bi [J]. Materials Transactions, 2017, 58(5): 720-723

[17] RamakrishnaV V, KavitaS, GautamR, RameshT, GopalanR. Investigation of structural and magnetic properties of Al and Cu doped MnBi alloy [J]. Journal of Magnetism and Magnetic Materials, 2018, 458: 23-29

[18] CéspedesE, VillanuevaM, NavíoC, MompeánF J, García-HernándezM, InchaustiA, PedrazP, OsorioM R, CamareroJ, BolleroA. High coercive LTP-MnBi for high temperature applications: From isolated particles to film-like structures [J]. Journal of Alloys and Compounds, 2017, 729: 1156-1164

[19] TerekhovA V, SolovjovA L, ProkhvatilovA I, MeleshkoV V, ZolochevskiiI V, CwikJ, LosA, ShevchenkoA D, IvasishinO M, KovalyukZ D. Anomalous anisotropic magnetoresistance and magnetization in Mn_3.69Bi_95.69Fe_0.62 [J]. East European Journal of Physics, 2017, 4(4): 12-17

[20] LiuB G, YuY T, PengJ H, SrinivasakannanC, ZhangL B, GuoS H. Preparation of microsized hematite powder from ferrous sulfate via microwave calcination [J]. Journal of Central South University, 2017, 24(8): 1720-1726

[21] NguyenT X, NguyenV V. Fabrication of MnBi alloys with high ferromagnetic phase content: Effects of heat treatment regimes and dopants [J]. Journal of Materials Science: Materials in Electronics, 2019, 30: 6888-6894

[22] KaushalS, GuptaD, BhowmickH. On development and wear behavior of microwave processed functionally graded Ni-SiC clads on SS-304 substrate [J]. Journal of Materials Engineering and Performance, 2018, 27(2): 777-786

[23] VorokhA S. Scherrer formula: Estimation of error in determining small nanoparticle size [J]. Nanosystems: Physics, Chemistry, Mathematics, 2018, 9(3): 364-369

[24] SirisathitkulC, CharoensukT. Effects of composition and heat treatment on manganese-bismuth magnets [J]. Micro & Nano Letters, 2019, 14(6): 661-664

[25] FangH L, LiJ H, ShafeieS, HedlundD, CedervallJ, EkstromF, GomezC S, BednarcikJ, SvedlindhP, GunnarssonK, SahlbergM. Insights into phase transitions and magnetism of MnBi crystals synthesized from self-flux [J]. Journal of Alloys and Compounds, 2019, 781: 308-314

[26] AnandK, ChristopherN, SinghN. Evaluation of structural and magnetic property of Cr-doped MnBi permanent magnet material [J]. Applied Physics A, 2019, 125: 870

[27] MoonK W, JeonK W, KangM, KangM K, ByunY, KimJ B, KimH, KimJ. Synthesis and magnetic properties of MnBi(LTP) magnets with high-energy product [J]. IEEE Transactions on Magnetics, 2014, 502103804

[28] ChenY, SawatzkiS, EnerS, Sepehri-AminH, LeineweberA, GregoriG, QuF, MuralidharS, OhkuboT, HonoK, GutfleischO, KronmüllerH, SchützG, GoeringE. On the synthesis and microstructure analysis of high permanence MnBi [J]. AIP Advances, 2016, 6125301

[29] LewisL H, CrewD C. The coercivity-remanence tradeoff in nanocrystalline permanent magnets [J]. Materials Research Society Symposia Proceedings, 2002, 703565-369

[30] ZhangW, BalasubramanianB, KharelP, PahariR, ValloppillyS R, LiX Z, YueL P, SkomskiR, SellmyerD J. High energy product of MnBi by field annealing and Sn alloying [J]. APL Materials, 2019, 7121111

[31] QianH D, ParkJ H, LimJ T, YangY, SiP Z, KimJ W, ChoiC J, ChoK M. Magnetic properties of MnBi bulk magnets with NaCl and C addition [J]. AIP Advances, 2019, 9115213