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Structure and approach to magnetic saturation in the Fe36Co36B19Si5Nb4 bulk amorphous alloy

Sabina T. Lesz 1Marcin G. Nabiałek 2Ryszard Nowosielski 1Jacek Olszewski 2

1. Silesian University of Technology, Institute of Engineering Materials and Biomaterials, ul. Konarskiego 18a, Gliwice 44-100, Poland
2. Institute of Physics, Częstochowa University of Technology, Al. Armii Krajowej 19, Częstochowa 42-200, Poland

Abstract

The idea of the paper is to study the structure and approach to magnetic saturation in the Fe36Co36B19Si5Nb4 bulk amorphous alloy in the shape rods with diameter of 1 and 2 mm. Investigated material were produced by the pressure die casting method. The ingot alloy was prepared by repeatedly inductive melting under a protective argon atmosphere using high purity elements. Subsequently, liquid melt was push out from quartz capillary to suitable rod forming copper die with using inert gas. The structure of obtained samples in solidified state was examined by X-ray diffraction (XRD) method and Mössbauer spectrometry.

From these studies we have stated that samples are fully amorphous. The regions with low and high density in the bulk amorphous alloys occur and due to magnetoelastic coupling influence the magnetization behavior in the vicinity of the ferromagnetic saturation. Any departure from the atoms system in liquid state be in thermodynamic equilibrium can be considered a defect in amorphous material [1].

Defects occurs in studied bulk ferromagnetic amorphous materials presenting source of short range stresses were investigated by indirectly method. These method was based on measurement of magnetization in high magnetic fields [2-4] by a vibrating sample magnetometer (VSM). In accordance to [1-4] magnetic polarization in high magnetic fields can be described by the equation:

m0M(H)=m0MS[1-Σi (ai)/(μ0H)i]+b(μ0H)1/2,

where:

m0MS- magnetic saturation polarization

μ0- magnetic permeability of free space,

H – magnetic intensity,

MS – magnetization intensity,

a, b – coefficents.

On the basis of results obtained by VSM method in high magnetic field it was observed that the diameter of rods (of the amorphous materials) has significant influence on size of defects. For all diameters of the analyzed alloy, important role in magnetization process in the vicinity of the ferromagnetic saturation plays sets of conglomeration of point-like defects, referred as quasi-dislocation dipoles.    For magnetic field above 1T, where the relation (μ0H)1/2 is valid for every diameter of the rod made of Fe36Co36B19Si5Nb4 alloy, the Holstein – Primakoff paraprocess connected with damping of thermal activation spine wave [5] is observed.

  1. N. Lange, H. Kronmüller “Low temperature magnetization of sputtered amorphous Fe – Ni – B films” Phys. Stat. Sol (A) 95, 2 (1986) 621-633.
  2. O. Kohmoto “High – field magnetization curves of amorphous alloys” Journal of Appl. Phys. 53, 11 (1982) 7486-7490.
  3. H. Kronmüller, M. Fähnle “Micromagnetism and the microstructure of ferromagnetic solids” Cambridge University Press (2003).
  4. M. Vazquez, W. Fernengel, H. Kronmüller “Approach to magnetic saturation in rapidly quenched amorphous alloys” Phys. Stat. Sol. (A) 115, 2 (1989) 547-553.
  5. T. Holstein, H. Primakoff “Field dependence of the intrinsic domain magnetization of a ferromagnet” Phys. Rev. 58 (1940) 1098 – 1113.
 

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Presentation: Poster at E-MRS Fall Meeting 2009, Symposium H, by Sabina T. Lesz
See On-line Journal of E-MRS Fall Meeting 2009

Submitted: 2009-05-22 19:18
Revised:   2009-06-07 00:48