Effects of Zr alloying on the microstructure and magnetic properties of Alnico permanent magnets

[Display omitted] Changes in magnetic properties as a function of Zr content. •Zr is added in Alnico permanent magnets (composition 32.5Fe-7.5Al-1.0Nb-35.0 Co-4.0Cu-14.0Ni-6.0Ti) up to 0.9wt%.•The optimum value of Zr is determined by applying magnetic field during cooling.•It is ascertained that 0.6...

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Veröffentlicht in:Journal of magnetism and magnetic materials 2017-11, Vol.442, p.136-140
Hauptverfasser: Rehman, Sajjad Ur, Ahmad, Zubair, Haq, A. ul, Akhtar, Saleem
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Sprache:eng
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Zusammenfassung:[Display omitted] Changes in magnetic properties as a function of Zr content. •Zr is added in Alnico permanent magnets (composition 32.5Fe-7.5Al-1.0Nb-35.0 Co-4.0Cu-14.0Ni-6.0Ti) up to 0.9wt%.•The optimum value of Zr is determined by applying magnetic field during cooling.•It is ascertained that 0.6wt% Zr is the optimum value.•The best magnetic properties obtained by thermo-magnetic annealing are Hc=1.64kOe, Br=6.3kG and (BH)max=3.7 MGOe.•The optical and HRSEM microstructure is presented. Alnico-8 permanent magnets were produced through casting and subsequent thermal treatment process. Magnetic alloy of nominal composition 32.5 Fe-7.5 Al-1.0 Nb-35.0 Co-4.0 Cu-14.0 Ni-6.0 Ti were prepared by arc melting and casting technique. The Zr was added to 32.5 Fe-7.5 Al-1.0 Nb-35.0 Co-4.0 Cu-14.0 Ni-6.0 Ti alloy ranging from 0.3 to 0.9wt%. The magnets were developed by employing two different heat treatment cycles known as conventional treatment and thermo-magnetic annealing treatment. The samples were characterized by X-ray diffraction method, Scanning electron microscope and magnetometer by plotting magnetic hysteresis demagnetization curves. The results indicate that magnetic properties are strongly depended upon alloy chemistry and process. The 0.6wt% Zr added alloys yielded the best magnetic properties among the studied alloys. The magnetic properties obtained through conventional heat treatment are Hc=1.35kOe, Br=5.2kG and (BH)max=2MGOe. These magnetic properties were enhanced to Hc=1.64kOe, Br=6.3kG and (BH)max=3.7MGOe by thermo-magnetic annealing treatment.
ISSN:0304-8853
1873-4766
DOI:10.1016/j.jmmm.2017.06.114