Crystallization kinetics and magnetic properties of Fe_73.5Si_13.5B₉Cu₁Nb₁V₂ nanocrystalline powder cores

Abstract

Amorphous ribbons of the alloy Fe_73.5Si_13.5B₉Cu₁Nb₁V₂ were prepared by the standard single copper wheel melt spinning technique in the air atmosphere. The crystallization kinetics of amorphous ribbons was analyzed by non-isothermal differential scanning calorimetry (DSC) measurements. The crystallization activation energies of amorphous ribbons calculated by using Kissinger model were 364 and 337 kJ/mol for the first and the second crystallization, respectively. The Avrami exponent n was calculated from the Johnson-Mehl-Avrami (JMA) equation. The value of the Avrami exponent showed that the crystallization mechanism in the non-isothermal primary crystallization of amorphous ribbons was all shapes growing from small dimensions controlled by diffusion at decreasing nucleation rate. The variation of soft magnetic properties of nanocrystalline Fe_73.5Si_13.5B₉Cu₁Nb₁V₂ alloy powder cores as a function of milling times has been investigated. It is found that the effective permeability of the cores shows high frequency stability and decreases with the increase of milling times. The quality factor increases with increasing frequency in lower frequency range, and reaches a maximum at the frequency of 80 kHz then decreases gradually with increasing frequency.

Keywords

finemet / crystallization kinetics / powder core

References

[1] Yoshizawa Y, Oguma S, Yamauchi K New Fe-based Soft Magnetic Alloys Composed of Ultrafine Grain Structure [J]. J. Appl. Phys., 1988, 64: 6 044-6 046.

[2] Herzer G Buschow K H J Nanocrystalline Soft Magnetic Alloys. Handbook of Magnetic Materials, vol.10[M], 1997 Amsterdam Elsevier

[3] Hono K, Hiraga K, Wang Q, . The Microstructure Evolution of a Fe_73.5Si_13.5B₉Nb₃Cu1 Nanocrystalline Soft Magnetic Materials [J]. Acta Metall. Mater., 1992, 40: 2 137-2 147.

[4] Barbatti C F, Sinnecker E H C P, Sarthour R S, . NMR Study of the Crystallization Kinetics in FINEMET-type Materials [J]. J. Alloys Compd., 2004, 369: 136-140.

[5] Herzer G Magnetization Process in Nanocrystalline Ferromagnets [J]. Mater. Sci. Eng. A, 1991, 133: 1-5.

[6] Herzer G Grain Structure and Magnetism of Nanocrystalline Ferromagnets [J]. IEEE Trans. Magn., 1989, 25: 3 327-3 329.

[7] Chau N, Chien N X, Hoa N Q, . Investigation of Nanocomposite Materials with Ultrasoft and High Performance Hard Magnetic Properties [J]. J. Magn. Magn. Mater., 2004, 282: 174-179.

[8] Chau N, Hoa N Q, Tho N D, . The Effect of Zn, Ag and Au Substitution for Cu in Finemet on the Crystallization and Magnetic Properties [J]. J. Magn. Magn. Mater., 2006, 303: e415-e418.

[9] Xu H, He K Y, Qiu Y Q, . Intense Milling Nanocrystalline Fe_73.5Cu1Nb₃Si_13.5B₉: a Soft Magnetic Material in Powdered Form [J]. Mater. Sci. Eng. A, 2000, 286: 197-200.

[10] Kim S W, Suk M J, Kim Y D, . Micro Metal Powder Injection Molding of W-Cu Nanocomposite Powder[J]. Met. Mater.:Int., 2005, 11: 205-208.

[11] Petzold J Application for Nanocrystalline Soft Magnetic Materials in Modern Electronic Devices [J]. Scrpita Mater., 2003, 48: 895-901.

[12] Hernando A, Marin P, Vazquez M, . Size Dependence of Coercivity in Nanostructured Soft Alloys [J]. Phys. Rev. B, 2004, 69: 052501

[13] Chiriac H, Moga A E, Urse M, . Structural and Magnetic Investigation of Mechanically Alloyed Fe₇₀Co_3.5Cu₁Nb₃B₉Si_13.5 Powder [J]. Nanostruct. Mater., 1999, 12: 495-498.

[14] Nowosielski R, Wyslocki J J, Wnuk I, . Nanocrystalline Soft Magnetic Composite Cores [J]. J. Mater. Process. Technol., 2006, 175: 324-329.

[15] Phan M H, Peng H X, Wisnom M R, . Effect of Annealing on the Microstructure and Magnetic Properties of Fe-based Nanocomposite Materials [J]. Composites: Part A, 2006, 37: 191-196.

[16] Lu W, Yan B, Huang W Complex Primary Crystallization Kinetics of Amorphous Finemet Alloy [J]. J. Non-Cryst. Solids, 2005, 351: 3 320-3 324.

[17] Kissinger H Reaction Kinetics in Differential Thermal Analysis [J]. Anal. Chem., 1957, 29: 1 702-1 706.

[18] Ozawa T A New Method of Analyzing Thermogravimetric Data [J]. Bull. Chem. Soc., 1965, 35: 1 881-1 886.

[19] Augis J A, Bennett J E B Calculation of the Avrami Parameters for Heterogeneous Solid State Reactions Using a Modification of the Kissinger Method [J]. J. Them. Anal., 1978, 13: 283-292.

[20] Barandiaran J M, Teller I, Garitaonandia J S, . Kinetic Aspects of Nano-crystallization in Finemet-like Alloys[J]. J. Non-Cryst. Solids, 2003, 329: 57-62.

[21] Crespo D, Pradell T, Clavaguera-Mora M T, . Microstructural Evaluation of Primary Crystallization With Diffusion-controlled Grain Growth [J]. Phys. Rev. B, 1997, 55: 3 435-3 444.

[22] Hampel G, Pundt A, Hesse J Crystallization of Fe_73.5Cu₁Nb₃Si_13.5B₉ Structure and Kinetics Examined by X-ray Diffraction and Mossbauer Effect Spectroscopy[J]. J. Phys.: Condens. Matter., 1992, 4: 3 195-3 214.

[23] Christian J M The Theory of Transformations in Metals and Alloys, 2nd Ed, 1975 New York Pergamon

[24] Malek J The Applicability of Johnson-Mehl-Avrami Model in the Thermal Analysis of the Crystallization Kinetics of Glasses [J]. Thermochimica Acta, 1995, 267(1): 61-73.

[25] Raja M M, Ponpandian N, Majumdar B, . Soft Magnetic Properties of Nanostructured FINEMET Alloy Powder Cores [J]. Mater. Sci. Eng. A, 2001, 304–306: 1 062-1 065.