Improving the hard magnetic properties by intragrain pinning for Ta doped nanocrystalline Ce-Fe-B alloys

doi:10.1016/j.jmst.2019.05.007

Abstract

Abstract:

To develop Ce based permanent magnets with high performance/cost ratio, Ta doping is was employed to enhance the magnetic performance of Ce-Fe-B alloys. For melt spun Ce₁₇Fe_78-_xTa_xB₆ (x = 0-1) alloys, the coercivity H_c increases from 439 to 553 kA/m with increasing x value from 0 to 0.75. Microstructure characterizations indicate that Ta doping is helpful for grain refinement. A second phase of TaB₂ is observed in Ce₁₇Fe_77.25Ta_0.75B₆ alloy, which acts as the pinning center of the magnetic domains, resulting in the change of coercivity mechanism from nucleation type to nucleation + pinning type. The micromagnetic simulation confirms that non-magnetic particles within hard magnetic phase can increase the demagnetization field around them and it is crucial for preventing the further magnetization reverse by pinning effect. Take the advantage of Ta doping for enhancing the coercivity, Ce content of Ce-Fe-B alloy can be further cut down to increase the remanence J_r due to the reduced volume fraction of CeFe₂ phase and increased Fe/Ce ratio. As a result, a good combination of magnetic properties with H_c = 514 kA/m, J_r = 0.49 T, and the maximum energy product (BH)_max = 36 kJ/m³ have been obtained in Ce₁₅Fe_79.25Ta_0.75B₆ alloy. It is expected that the present work can serve as a useful reference for designing new permanent magnetic materials with low-cost.

Key words: Melt-spinning, Permanent magnets, Second phase, Coercivity mechanism, Thermal stability

J.S. Zhang, W. Li, X.F. Liao, H.Y. Yu, L.Z. Zhao, H.X. Zeng, D.R. Peng, Z.W. Liu. Improving the hard magnetic properties by intragrain pinning for Ta doped nanocrystalline Ce-Fe-B alloys[J]. J. Mater. Sci. Technol., 2019, 35(9): 1877-1885.

Figures/Tables 11

Fig. 1. Demagnetization curves (a) and magnetic properties (b) of the as-spun Ce17Fe78-xTaxB6 alloys.

Fig. 2. Refined XRD patterns of the as-spun Ce17-xFe78-x+yTaxB6 alloys.

Fig. 3. (a) Dependences of lattice parameters a, c, c/a of the 2:14:1 phase, (b) lattice parameters a of 1:2 phase on the Ta content x for Ce17Fe78-xTaxB6 alloys.

Fig. 4. Bright-field TEM image of the Ce17Fe78-xTaxB6 alloys with (a) x = 0 and (b) x = 0.75, insets in (a) and (b) is the histogram of grain sizes.

Fig. 5. Mapping of elements distributions in the Ce17Fe77.25Ta0.75B6 alloy: the image in STEM HAADF mode (a) and the distribution of (b) Ce element, (c) Fe element, and (d) Ta element.

Fig. 6. TEM images of the Ce17Fe77.25Ta0.75B6 alloy: (a) Bright-field TEM image and the EDS results of spot A, B and C. The HRTEM images of grain A and grain C are shown in Fig. (b) and Fig. (c) (d). Fast Fourier Transformation (FFT) for the HRTEM images of the grain in Fig. (b), Fig. (c) and Fig. (d) are shown in Figs. (e), (f) and (g), respectively.

Fig. 7. Simulation results on pinning and without pinning models. (a) Simulation model consisting of two non-magnetic grains within each Ce2Fe14B grain for pinning effects. (b) Demagnetization curves and their fitting line corresponding to the models w/ and w/o particles, the inset shows experimental M?H curves for x = 0 and x = 0.75 alloys. (c) Demagnetizing field distribution in the section of x = 130 nm for both models in the saturation state. (d) Magnetization reversal behaviors in the section of x = 130 nm for both models at different reversed magnetic field marked in (a).

Fig. 8. Plot of μ0Hc(T)/Js(T) vs μ0Ha(T)/Js(T) for (a) Ce17Fe78B6 and (b) Ce17Fe77.25Ta0.75B6 alloys. Plot of [Hc(T)]1/2 vs [T(K)]2/3 for (c) Ce17Fe78B6 and (d) Ce17Fe77.25Ta0.75B6 alloys.

Fig. 9. Demagnetization curves (a) and magnetic properties (b) of the melt spun Ce17-yFe77.25+yTa0.75B6 alloys.

Fig. 10. Refined XRD patterns of the as-spun Ce17-yFe77.25+yTa0.75B6 alloys.

Table 1 Magnetic properties of melt-spun Ce-(M)-Fe-B alloys in the current work and reported in other literature.

	Composition	H_cj (kA/m)	J_r (T)	(BH)_max (kJ/m³)	Annealing temperature (℃)	Ref.
Ce-Fe-Ta-B	Ce₁₇Fe₇₈B₆	439	0.47	35	/	This work
	Ce₁₇Fe_77.25Ta_0.75B₆	553	0.45	32	/	This work
	Ce₁₅Fe_79.25Ta_0.75B₆	514	0.49	36	/	This work
	Ce₁₄Fe_80.25Ta_0.75B₆	448	0.54	41	/	This work
	Ce₁₃Fe_81.25Ta_0.75B₆	387	0.59	47	/	This work
Ce-Fe-M-B	Ce₁₇Fe_77.25B₆Ga_0.75	492	0.43	19	/	[18]
	Ce₁₇Fe_77.5B₆Zr_0.5	430	0.48	36	788	[35]
	Ce₁₇Fe₇₇B₆Hf	420	0.38	/	/	[36]
	Ce₃Fe₁₂Co₂B	390	0.52	35	/	[17]

References

[1]	S. Sugimoto,J. Phys.D-Appl. Phys. 44(2011), 064001.
[2]	J. Coey, Scr. Mater. 67(2012) 524-529.
[3]	M. Hussain, L. Zhao, C. Zhang, D. Jiao, X. Zhong, Z. Liu, Phys. B. 483(2016)69-74.
[4]	Q. Jiang, Z. Zhong, J. Mater. Sci.Technol. 33(2017) 1087-1096.
[5]	A. Alam, M. Khan, R.W. McCallum, D.D. Johnson,Appl. Phys. Lett. 102(2013),042402.
[6]	A. Alam, D.D. Johnson,Phys. Rev. B 89 (2014), 235126.
[7]	D.C. Koskenmaki, K.A. North Holland, 1978, pp. 337-377.
[8]	J. Herbst, M. Meyer, F. Pinkerton,J. Appl. Phys. 111 (2012), 07A718.
[9]	Z. Zhang, L. Zhao, X. Zhong, D. Jiao, Z. Liu, J. Magn. Magn.Mater. 441(2017)429-435.
[10]	L. Zhao, H. Yu, W. Guo, J. Zhang, Z. Zhang, M. Hussain, Z. Liu, J.M. Greneche,IEEE Trans. Magn. 53 (11) (2017) 1-5.
[11]	L. Paolasini, P. Dervenagas, P. Vulliet, J.P. Sanchez, G. Lander, A. Hiess, A. Panchula, P. Canfield, Phys. Rev. B 58 (1998) 12117.
[12]	Y. Zhang, T. Ma, J. Jin, J. Li, C. Wu, B. Shen, M. Yan, Acta Mater. 128(2017)22-30.
[13]	Q. Zhou, Z. Liu, S. Guo, A. Yan, D. Lee, IEEE Trans. Magn. 51(2015) 1-4.
[14]	R. Wang, Y. Liu, J. Li, W. Zhao, X. Yang, J. Mater. Sci. 52(2017) 7311-7322.
[15]	X. Tang, H. Sepehri-Amin, T. Ohkubo, M. Yano, M. Ito, A. Kato, N. Sakuma, T. Shoji, T. Schrefl, K. Hono, Acta Mater. 144(2018) 884-895.
[16]	L. Zhao, W. Guo, Z. Zhang, D. Jiao, J. Zhang, Z. Liu, J. Greneche, J. Alloys Compd.715(2017) 60-64.
[17]	E.J. Skoug, M. Meyer, F. Pinkerton, M.M. Tessema, D. Haddad, J. Herbst, J.Alloys Compd. 574(2013) 552-555.
[18]	Q. Jiang, M. Zhong, W. Lei, Q. Zeng, Y. Hu, Q. Quan, Y. Xu, X. Hu, L. Zhang, R. Liu,AIP Adv. 7(2017), 085013.
[19]	J. Zhang, L. Zhao, X. Liao, H. Zeng, D. Peng, H. Yu, X. Zhong, Z. Liu,Intermetallics 107 (2019) 75-80.
[20]	E. Burzo, Rep. Prog. Phys. 61(1998) 1099.
[21]	T. Chin, C. Lin, Y. Huang, J. Yau, S. Heh, F. King, IEEE Trans. Magn. 29(1993)2788-2790.
[22]	Z. Liu, Y. Liu, P. Deheri, R. Ramanujan, H. Davies, J. Magn. Magn.Mater. 321(2009) 2290-2295.
[23]	S.U. Rehman, Q. Jiang, W. Lei, L. Zeng, Q. Tan, M. Ghazanfar, S.U. Awan, T. Ahmad, M. Zhong, Z. Zhong, J. Phys. Chem. Solids 124 (2018) 261-265.
[24]	T.S. Chin, S. Huang, J. Yau, Appl. Phys. Lett. 59(1991) 2046-2048.
[25]	D. Tang, Y. Liu, J. Li, X. Liu, Q. Zhou, J. Magn. Magn.Mater. 460(2018) 263-267.
[26]	H. Chang, M. Shih, C. Hsieh, W. Chang, J. Alloys. Compd. 484(2009) 143-146.
[27]	Q.Z. Jiang, M.L. Zhong, Q.C. Quan, J.S. Zhang, Z.C. Zhong, J. Alloys. Compd. 688(2016) 363-367.
[28]	Y.Q. Wu, M. Kramer, Z. Chen, B.-M. Ma, D. Ping, K. Hono, IEEE Trans. Magn. 39(2003) 2935-2937.
[29]	M. Donahue, , 1998.
[30]	J. Bauer, M. Seeger, A. Zern, H. Kronmüller, J. Appl. Phys. 80(1996) 1667-1673.
[31]	D. Goll, M. Seeger, H. Kronmüller, J. Magn. Magn.Mater. 185(1998) 49-60.
[32]	P. Gaunt, Philos. Mag. B. 48(1983) 261-276.
[33]	M. Hussain, J. Liu, L. Zhao, X. Zhong, G. Zhang, Z. Liu, J. Magn. Magn.Mater. 399(2016) 26-31.
[34]	Q.Y. Zhou, Z. Liu, S. Guo, A.R. Yan, D. Lee, IEEE Trans. Magn. (2015) 1-4.
[35]	B. Ni, H. Xu, X. Tan, X. Hou, J. Magn. Magn.Mater. 401(2016) 784-787.
[36]	Q. Jiang, M. Zhong, Q. Quan, W. Lei, Q. Zeng, Y. Hu, Y. Xu, X. Hu, L. Zhang, R. Liu,J. Magn. Magn.Mater. 444(2017) 344-348.