Effect of Sb substitution on crystal structure, texture and hard magnetic properties of melt-spun MnBi alloys

JOURNAL OF ALLOYS AND COMPOUNDS

卷:792

Article

Gabay, A. M.¹  Hadjipanayis, G. C.¹  Cui, J.² 

[1] Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA

[2] Iowa State Univ, Dept Mat Sci & Engn, Ames, IA 50011 USA

关键词: Intermetallics;    Permanent magnets;    Nanostructured materials;    Rapid solidification;    Crystal structure;    Magnetization;   

DOI  :  10.1016/j.jallcom.2019.03.407

来源: Elsevier

【 摘 要 】

Melt-spun Mn50Bi50-xSbx alloys with x <= 5 were prepared at different solidification rates and characterized both in the as-spun state and after annealing. In the as-spun alloys, the Sb substitution leads to the formation of a metastable phase, similar to the binary quenched high-temperature phase but without the superstructure of the latter and exhibiting a different e increasing e temperature dependence of coercivity. The new nanocrystalline metastable phase is not only itself characterized by a high room-temperature coercivity (in excess of 20 kOe), but upon annealing it transforms into a highcoercivity (up to 13.5 kOe) low-temperature a phase. However, the advantage of obtaining a high coercivity without the otherwise required milling made possible by the Sb substitution is undermined by the absence of a local crystallographic texture in the melt-spun alloys. The best combination of the isotropic hard magnetic properties realized for the Mn55Bi43.5Sb1.5 composition is a remanence of 35.5 emu/g and a coercivity of 8.1 kOe. The annealed Sb-free Mn50Bi50 alloys did possess a local crystallographic alignment and, for high solidification rates, a moderate coercivity up to 5.6 kOe; however, they had an inadequaterectangularity in the demagnetization curve. The orthorhombic compound known as MnBi0.9Sb0.1 and described earlier as antiferromagnetic was obtained in the annealed ribbons with x=5. The compound was found to order ferromagnetically between 200 K and z250 K and to exhibit a significant coercivity, 14.3 kOe at 50 K. It is suggested that the MnBi0.9Sb0.1 may actually be a Sb-stabilized new phase observed earlier as metastable in the BieMnBi eutectic alloys. (c) 2019 Elsevier B.V. All rights reserved.

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