Effect of Co, Ti and Cr Additions on Microstructure, Magnetic Properties and Corrosion Resistance of Magnetocaloric Gd-Ge-Si Alloys

Mariusz Hasiak; Jacek G Chęcmanowski; Barbara Kucharska; Amadeusz Łaszcz; Aleksandra Kolano-Burian; Jerzy Kaleta

doi:10.3390/ma13245758

Effect of Co, Ti and Cr Additions on Microstructure, Magnetic Properties and Corrosion Resistance of Magnetocaloric Gd-Ge-Si Alloys

Materials (Basel). 2020 Dec 17;13(24):5758. doi: 10.3390/ma13245758.

Authors

Mariusz Hasiak¹, Jacek G Chęcmanowski², Barbara Kucharska³, Amadeusz Łaszcz¹, Aleksandra Kolano-Burian⁴, Jerzy Kaleta¹

Affiliations

¹ Department of Mechanics, Materials and Biomedical Engineering, Wrocław University of Science and Technology, 25 Smoluchowskiego, 50-370 Wrocław, Poland.
² Department of Advanced Materials Technologies, Wrocław University of Science and Technology, 25 Smoluchowskiego, 50-370 Wrocław, Poland.
³ Department of Materials Engineering, Częstochowa University of Technology, 19 Armii Krajowej, 42-200 Częstochowa, Poland.
⁴ Łukasiewicz Research Network, Institute of Non-Ferrous Metals, 5 Sowińskiego, 44-100 Gliwice, Poland.

Abstract

The paper presents studies of microstructure, magnetic and corrosion properties of the Gd₅₈Ge₂₀Si₂₂, Gd₅₆Ge₂₀Si₂₂Co₂, Gd₅₆Ge₂₀Si₂₂Ti₂ and Gd₅₆Ge₂₀Si₂₂Cr₂ (at.%) alloys after isothermal heat treatment at 1450 K for 2 h. The structure investigations of the produced materials performed by X-ray diffraction show the presence of Gd₅Ge₂Si₂-type phase in all investigated samples. DC and AC magnetic measurements confirmed that the Curie temperature depends on the chemical composition of the produced alloys. From M(T) characteristics, it was found that the lowest Curie point (T_C = 268 K) was estimated for the Gd₅₈Ge₂₀Si₂₂ sample, whereas the highest value of the Curie temperature (T_C = 308 K) was for the Gd₅₆Ge₂₀Si₂₂Cr₂ alloys. Moreover, the GdGeSi alloy without alloying additions shows the highest magnetic entropy change |ΔS_M| = 15.07 J⋅kg^-1⋅K^-1 for the maximum magnetic field of 2 T. The maximum |ΔS_M| measured for the Gd₅₆Ge₂₀Si₂₂ with the addition of Co, Ti or Cr for the same magnetic field was obtained in the vicinity of the Curie point and equals to 2.92, 2.73 and 2.95 J⋅kg^-1⋅K^-1, respectively. Electrochemical studies of the produced materials for 60 min and 55 days exposure in 3% NaCl solution show that the highest stability and corrosion resistance were exhibited the sample with added of Ti.

Keywords: GdGeSi-based alloys; corrosion resistance; magnetic properties; magnetocaloric effect; microstructure.