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This paper presents domain and structure studies of bonded magnets made from nanocrystalline Nd-(Fe, Co)-B powder. The structure studies were investigated using scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Mössbauer spectroscopy and X-ray diffractometry. On the basis of performed qualitative and quantitative phase composition studies, it was found that investigated alloy was mainly composed of Nd2(Fe-Co)14B hard magnetic phase (98 vol%) and a small amount of Nd1.1Fe4B4 paramagnetic phase (2 vol%). The best fit of grain size distribution was achieved for the lognormal function. The mean grain size determined from transmission electron microscopy (TEM) images on the basis of grain size distribution and diffraction pattern using the Bragg equation was about ≈130 nm. HRTEM images showed that over-stoichiometric Nd was mainly distributed on the grain boundaries as a thin amorphous border of 2 nm in width. The domain structure was investigated using a scanning electron microscope and metallographic light microscope, respectively, by Bitter and Kerr methods, and by magnetic force microscopy. Domain structure studies revealed that the observed domain structure had a labyrinth shape, which is typically observed in magnets, where strong exchange interactions between grains are present. The analysis of the domain structure in different states of magnetization revealed the dynamics of the reversal magnetization process.

The fabrication method and magnetic properties of Sm12.5Co66.5Fe8Cu11Si2 alloy are presented in this article. The samples were produced by rapid quenching of the liquid alloy onto a rotating, copper wheel (the so-called ‘melt-spinning’ method) and they had a thin ribbon shape. The microstructure of the samples was investigated by measurements of diffraction patterns for powdered samples, in order to obtain data from the entire volume of the sample. It was found, that samples were composed of different amounts of Sm2Co17, SmCo5 and SmCo7 phases, depending on the linear velocity of the copper wheel used during the fabrication process. The magnetic measurements were performed using a vibrating sample magnetometer (LakeShore VSM) working with an external magnetic field of up to 2 T. It was found that the obtained ribbons displayed relatively good hard magnetic properties, such as remanence μ0MR, and high resistance to demagnetization fields JHC.

The aim of this paper is to present the results of crystallization studies for the bulk amorphous (Fe0.61Co0.10Zr0.025Hf0.025 Ti0.02W0.02B0.20)98Y2, Fe61Co10TixY6B20, Fe61Co10Ti2Y7B20 alloys. The crystallization of the alloys was studied by differential scanning calorimetry (DSC). The amorphicity of the investigated alloys in the as-quenched state was testified using Mossbauer spectroscopy, X-ray diffractometry and transmission electron microscopy. Moreover, X-ray diffractometry was applied to structure investigations of partially crystallized samples. The crystallization process in the investigated alloys occurs in one or two stages. Two peaks in the DSC curves can be overlapped or well separated indicating the complex crystallization processes. From X-ray diffraction we have stated that in both types of devitrification the crystalline phase can be ascribed to the α-FeCo. In the first stage the crystalline grains seem to grow from the nuclei frozen in the samples during the rapid quenching, whereas in the second one both the growth of the existed grains and creation of new ones during annealing may occur.

Modern Re-Fe-B hard magnetic materials, produced using rapid quenching technique, taking into account variations in chemical composition, can be divided into three groups i.e. of stoichiometric, Re2Fe14B composition, and with excess of rare earth or iron [1–3]. Materials, composed of Re-Fe-B compound with overstoichiometric rare earths, typically are characterized by worse glass transition ability, smallest Mr/Ms ratio and large coercivity. Their properties are shaped by exchange interactions between Re2Fe14B, which are weakened by an increased distance between the grains. Enlarged distance between grains is resulting from the presence of a thin boundary formed from an amorphous matrix of redundant rare earths. Additionally, the presence of such a boundary causes an increase in coercivity due to the strong bonding of domain walls at the grain boundaries [4]. The stoichiometric composition causes increase in glass transition ability, Mr/Ms ratio but also causes deterioration of coercivity. These changes are a result of a reduction in the distance between grains, by removing the paramagnetic amorphous matrix, and fi ner structure as a result of increase in glass transition ability [5]. The highest glass transition ability, fi ner structure and highest Mr/Ms ratio is met in Re-Fe-B compound with overstoichiometric iron. The signifi cantly higher value of the Mr/Ms ratio results from the presence of the strong exchange interactions, between particles that differ in magnetic hardness. The grains, of soft magnetic phase, have The microstructure and magnetic properties of Nd8.5Tb1.5Fe83Zr1B6 ribbons obtained at various cooling rates Marcin Dośpial, Jacek Olszewski, Marcin Nabialek, Pawel Pietrusiewicz, Tomasz Kaczmarzyk

The properties of metallic amorphous materials depend mainly on their chemical composition and the degree of relaxation of the structure. The relaxed amorphous structure is usually obtained by annealing below the crystallization temperature ( T x ). However, this process can be forced during the production process. In this paper, the results are presented of investigations into the: microstructure, magnetic and mechanical properties of Fe 61 Co 10 Y 8 W 1 B 20 alloy. The samples, fabricated in the forms of ribbons and plates, were produced using cooling speeds of 10 4 –10 6 K/s and 10 1 –10 3 K/s, respectively. In the course of the investigations, it has been found that varying the quenching speed of the liquid alloy has a major influence on the properties of the Fe 61 Co 10 Y 8 W 1 B 20 amorphous alloys.

Amorphous Fe 61 Co 10 Zr 4− x Y 2+ x Nb 5 B 15 ( x = 0, 1) samples in the form of a ribbon with a thickness of approximately 30 μm and a width of about 4 mm have been investigated. The ribbons were obtained by a single roller melt-spinning method with the wheel linear velocity equal to 35 m/s. Microstructural studies, using X-ray spectroscopy, confirmed that samples in the as-quenched state were fully amorphous. Measurements carried out using a vibrating sample magnetometer allowed values of coercivity and saturation magnetization to be obtained. On the basis of performed measurements, it can be stated that Fe 61 Co 8 Zr 4 Y 2 Ni 5 Nb 5 B 15 alloy exhibits superior soft magnetic properties compared with the Fe 61 Co 8 Zr 3 Y 3 Ni 5 Nb 5 B 15 alloy. The former alloy possesses: a higher value of saturation magnetization, almost double the value of magnetic permeability, approximately half the value of coercivity and substantially smaller core losses than the latter alloy.

Influence of Heat Treatment on Magnetic Properties of Nanocrystalline Nd9Fe84Zr1B6Ribbons Received by Rapid Solidification MethodThe effect of the annealing on the phase composition and magnetic properties of nanocomposite melt-spun Nd9Fe84Zr1B6ribbons has been investigated. From the X-ray diffraction studies confirmed be thermomagnetic curves measurements results that the microstructure of the material investigated is composed of a mixture of magnetically hard Nd2Fe14B and soft α-Fe, Fe3B nanosized grains. The small amount of undesirable Nd2Fe23B3metastable phase has been found which do not decompose at the highest annealing temperature. The hysteresis loop measurements certify that the ribbon annealed at 863K show the best coupling between the hard and soft magnetic phases and thus the highest coercivity of 0.38T. The grain sizes increase with increasing annealing temperature causing the coercivity to be decrease.

In this article, one of the production method of Fe based amorphous metallic materials, exhibiting excellent soft magnetic properties was described. The presented method consists in the unidirectional casting of the liquid alloy on to rotating, at high frequency, copper wheel. The produced samples had a ribbon shape with a thickness of about 45 microns. Apply this method allows to obtain materials exhibiting the lack of long-range ordering between the atoms and characterized by unique magnetic and mechanical properties. The structure of produced samples was investigated using Mössbauer spectroscopy and X-ray diffraction. The saturation magnetization (μ0MS) and coercivity field (Hc) of ribbons in the as-cast state, have values corresponding to materials, with good soft ferromagnetic properties.On the basis of structural and magnetic investigations, it was found that the obtained samples were amorphous and had very good magnetic properties. That allows us to think, that the presented method makes it possible to fabricate the amorphous materials, characterized by the good electrotechnical parameters.

Recently bulk amorphous alloys have attracted great attention due to their excellent magnetic properties. The glass-forming ability of bulk amorphous alloys depends on the temperature difference (Δ T x ) between glass transition temperature ( T g ) and crystallization temperature ( T x ). The increase of Δ T x causes a decrease of the critical cooling rate ( V c ) and growth of the maximum casting thickness of bulk amorphous alloys. The aim of the present paper is to characterize the structure, the thermal stability and magnetic properties of Fe 36 Co 36 B 19 Si 5 Nb 4 bulk amorphous alloys using XRD, Mossbauer spectroscopy, DSC and VSM methods. Additionally the magnetic permeability μ i (at force H ≈ 0.5 A/m and frequency f ≈ 1 kHz) and the intensity of disaccommodation of magnetic permeability Δ μ / μ ( t 1 ) (Δ μ = μ ( t 1 = 30 s) − μ ( t 2 = 1800 s)), have been measured, where μ is the initial magnetic permeability measured at time t after demagnetisation, the Curie temperature T C and coercive force H c of rods are also determined with the use of a magnetic balance and coercivemeter, respectively. Fe–Co–B–Si–Nb bulk amorphous alloys were produced by pressure die casting with the maximum diameters of 1 mm, 2 mm and 3 mm. The glass transition temperature ( T g ) of studied amorphous alloys increases from 807 K for a rod with a diameter of 1 mm to 811 K concerning a sample with a diameter of 3 mm. The crystallization temperature ( T x ) has the value of 838 K and 839 K for rods with the diameters of 1 mm and 3 mm, respectively. The supercooled liquid region (Δ T x = T x − T g ) has the value of about 30 K. These values are presumed to be the origin for the achievement of a good glass-forming ability of the Fe–Co–B–Si–Nb bulk amorphous alloy. The investigated amorphous alloys in the form of rods have good soft magnetic properties (e.g. M s = 1.18–1.24 T). The changes of crystallization temperatures and magnetic properties as a function of the diameter of the rods (time of solidification) have been stated.

The microstructure, magnetic properties and thermal stability of Fe61Co10Zr2.5Hf2.5Me2W2B20 (Me = Y, Nb, W, Ti, Mo, Ni) alloys were investigated. The samples were obtained by an induction suction method as 0.5 mm thickness plates. The microstructure was examined using X-ray diffraction and Mossbauer spectroscopy. It was shown that the investigated samples have amorphous structure throughout the volumes of the samples. The magnetic properties were measured using a Vibrating Sample Magnetometer. The investigated alloys are soft magnetic materials with low coercivity field (from 5.8 A/m to 54 A/m) and high saturation of the magnetization (from 0.87 T to 1.26 T). The studies of thermal stability were performed using a differential scanning calorimeter. It was shown that the addition of respective atoms led to changes of Curie temperature in the range from 497 to 587 K, depending on the composition of the alloys.

Amorphous samples of the Fe61Co10Y8Nb1B20 alloy in the form of a ribbon with thickness of approximately 30 μm and in the form of a plate with thickness of 0.5 mm have been investigated. Plates were obtained by a suction-casting method, and ribbons by a single roller melt-spinning method. Microstructural studies, using X-ray spectroscopy, confirmed that samples in the as-quenched state were fully amorphous. Measurements carried out using a vibrating sample magnetometer allowed values of coercivity and saturation magnetization to be obtained; it also facilitated the estimation of size and nature of structural defects in the investigated samples. All of the investigated samples of this alloy in the as-quenched state have high values of saturation magnetization of greater than 1.25 T.

3) belong to a group of hard magnetic materials,with excellent magnetic properties. Their unique proper-ties are determined by: high density of the nal magnet,and a signi cant degree of crystallographic texture. Thedensities of the produced magnets are in range from 91%to 99.6% of the densities of powders used in productionprocess [1]. The crystallographic texture, obtained in thedeformation process, results in formation of large mag-netocrystalline anisotrop,ywhich has signi cant in uenceon the magnetic parameters.In the literature there can be found many studies onthe e ects of deformation conditions, such as a temper-ature, time, applied force and grain size on the mag-netic and mechanical properties of the produced magnets[1 5]. While, there is not much studies in which the sub-ject of discussion are reversal magnetization mechanismsoccurring in hot deformed magnets [6, 7] and the in u-ence of ariousv production conditions on the

The Domain Structure of Die-Upset Anisotropic Magnet Based On Nd-(Fe, Co)-B Alloy The measurements of the recoil curves for the die-upset Nd-(Fe, Co)-B based magnets from different points on the magnetization and demagnetization curves have been carried out by means of the LakeShore vibrating sample magnetometer in an applied magnetic fields up to 2 T. From the recoil curves the so-called Wohlfarth's remanence relationship has been derived. From this it was deduced that the magnetic interaction existing between the magnet grains has a dipolar nature. The existence of the magnetic interaction has been confirmed by magnetic domain observations by using the magnetic force microscopy (MFM). In the area of interaction domains there is the fine scale magnetic contrast resulting from the dipolar interaction between neighboring grains.