ORALS

SESSION: SISAMSatPM2-R3 H: Characterization cont.	Kobe International Symposium on Science of Innovative and Sustainable Alloys and Magnets (5th Intl. Symp. on Science of Intelligent and Sustainable Advanced Materials (SISAM))
Sat Oct, 26 2019 / Room: Dr. Christian Bernard
Session Chairs: Petra Jenus; Session Monitor: TBA

15:55: [SISAMSatPM209]
Amorphous Al-Ce-Cu-Fe alloys: Glass formation and properties
Luka Kelhar¹ ; Spomenka Kobe² ; Jean-marie Dubois³ ; ¹JSI - K7 Dpt, Ljubljana, Slovenia; ²Josef Stefan Institute, Ljubljana, Slovenia; ³JSI - K7 Dpt for Nanostructured Materials, Ljubljana, Slovenia;
Paper Id: 275 [Abstract]

The Al-Cu-Fe system is well known, for it contains a quasicrystal, the ultimate degree of lattice complexity in an ordered solid. Susbtitution of Ce for Al atoms cancels the formation of the quasicrystals, but favours amorphisation upon rapid solidification from the liquid state. We have accordingly studied the solubility range of Ce in this alloy when replacing Al atoms. We have varied the Cu/Fe ratio at constant Al,Ce concentration as well. We found evidence that the local order in the glass is predominantly icosahedral, which matches the evidence of a very low glass transition temperature in the vicinity of the eutectic concentration known in the binary Al-Ce system. This interesting result can be exploited to prepare bulk specimens by spark plasma sintering, a technique that we used to produce centime-wide specimens. The magnetic properties were studied in a wide composition range and will be reported in the talk.

SESSION: SISAMSatPM2-R3 H: Characterization cont.	Kobe International Symposium on Science of Innovative and Sustainable Alloys and Magnets (5th Intl. Symp. on Science of Intelligent and Sustainable Advanced Materials (SISAM))
Sat Oct, 26 2019 / Room: Dr. Christian Bernard
Session Chairs: Petra Jenus; Session Monitor: TBA

16:45: [SISAMSatPM211]
Metal-Bonded Magnets Based on YCo5-Type Nanocrystals
Marko Soderžnik¹ ; Matic Korent² ; Kristina Zagar Soderznik³ ; Jean-marie Dubois⁴ ; Pelin Tozman⁵ ; M. Venkatesan⁶ ; Michael Coey⁷ ; Spomenka Kobe⁸ ; ¹Jožef Stefan Institute, Ljubljana, Slovenia; ²Jozzef Stefan Institute, LJUBLJANA, Slovenia; ³Jozef Stefan Institute, Ljubljana, Slovenia; ⁴JSI - K7 Dpt for Nanostructured Materials, Ljubljana, Slovenia; ⁵NIMS, Tsukuba, Japan; ⁶School of Physics and CRANN, Trinity College, Dublin, Ireland; ⁷School of Physics, Dublin, Ireland; ⁸Josef Stefan Institute, Ljubljana, Slovenia;
Paper Id: 342 [Abstract]

Metal-bonded magnets based on YCo₅-type nanocrystals [i] were produced by hot-compaction using a spark plasma-sintering device. Zn and Zn/Al metallic binders with a melting temperature of ̴ 420°C were employed to fabricate dense cylindrical magnets. Two different pressures were used for compaction. The pressure of 400 MPa provided a metal-bonded magnet with Vickers hardness (HV10) of 460 ± 20 Vickers. The temperature coefficients for remanence (α) and coercivity (β) were derived from magnetization vs. magnetic field measurements in the temperature range of 20°C – 150°C. Temperature coefficients α and β for the Zn/Al-bonded magnet pressed with 400 MPa were -0.055 %/°C and -0.201 %/°C, respectively. The field emission gun scanning electron microscope revealed a ‘core-shell’-type microstructure. The pure YCo_4.8Fe_0.2 phase was detected in the core region whereas the shell was enriched with non-ferromagnetic Zn or Zn/Al phases. The high-resolution transmission electron microscope revealed the presence of clusters with ̴ 20 nm YCo_4.8Fe_0.2 grains. In the Zn/Al-bonded magnet, fabricated at 400 MPa, the coercivity <i>µ₀H_ci</i>, remanent magnetization σ and energy product (BH)_max were 0.87 T, 39.3 Am²/kg and 23.4 kJ/m³, respectively.[ii]

References:
[i] P. Tozman, M. Venkatesan, J. M. D. Coey, Optimization of the magnetic properties of nanostructured Y-Co-Fe alloys for permanent magnets, AIP Adv. 6 (2016) 056016.\n[ii] M. Soderžnik, M. Korent, K. Žagar Soderžnik, J.-M. Dubois, P. Tozman, M. Venkatesan, J. M. D. Coey, S. Kobe, Hot-compaction of YCo4.8Fe0.2 nanocrystals for metal-bonded magnets, J. Mag. and Magn. Mat. 460 (2018) 401-408.