The Process of Magnetizing FeNbYHfB Bulk Amorphous Alloys in Strong Magnetic Fields

Abstract

The structure of amorphous alloys still has not been described satisfactorily due to the lack of direct methods for observing structural defects. The magnetizing process of amorphous alloys is closely related to its disordered structure. The sensitivity of the magnetization vector to any heterogeneity allows indirect assessment of the structure of amorphous ferromagnetic alloys. In strong magnetic fields, the magnetization process involves the rotation of a magnetization vector around point and line defects. Based on analysis of primary magnetization curves, it is possible to identify the type of these defects. This paper presents the results of research into the magnetization process of amorphous alloys that are based on iron, in the areas called the approach to ferromagnetic saturation and the Holstein-Primakoff para-process. The structure of a range of specially produced materials was examined using X-ray diffraction. Primary magnetization curves were measured over the range of 0 to 2 T. The process of magnetizing all of the tested alloys was associated with the presence of linear defects, satisfying the relationship D di p < 1 H . It was found that the addition of yttrium, at the expense of hafnium, impedes the magnetization process. The alloy with an atomic content of Y = 10% was characterized by the highest saturation magnetization value and the lowest value of the D spf parameter, which may indicate the occurrence of antiferromagnetic ordering in certain regions of this alloy sample.produced in the form of thin ribbons, using the melt-spinning method [4], present particularly good properties. Materials of this type are characterized by a high value of saturation magnetization (above 1.5 T) and a low value of coercive field (approximately 1 A/m) [5][6][7][8][9]. These material samples are extremely easy to magnetize, partly due to their dimensions. Amorphous ribbons have thicknesses of up to several tens of µm. Unfortunately, these dimensions significantly limit the applications of these materials. The so-called bulk amorphous alloys comprise a relatively new group of promising materials. These materials are produced by a rapid-quenching process in copper molds. The most well-known production methods are the injection-and suction-casting methods [10,11]. In this way, at a cooling rate of 10 −1 -10 3 K/s, iron-based alloys with dimensions exceeding 10 mm can be produced [12][13][14]. However, due to their high proportions of non-magnetic component elements, such as: B, C, Zr, Y, Mo, Nb, Hf, or Cr, these alloys do not exhibit the best magnetic properties. A compromise that combines relatively good magnetic properties (saturation magnetization greater than1T, coercive field less than 50 A/m) with favorable alloy geometry (diameter up to 3 mm) exists in the form of alloys with a content of approximately 65%-75% magnetic elements [15][16][17][18].The process of magnetizing amorphous alloys does not differ significantly from their crystalline counterparts. Figure 1 shows a diagram of the primary magnetization cur...

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