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Hydrogenated La(Fe,Mn,Si)13-based alloys have an excellent magnetocaloric properties, but poor mechanical and chemical stability. This hinders their direct machining and implementation in an active magnetic regenerator (AMR). In this paper, we show how machinability and corrosion protection of the particles can be improved by a hot-dip coating. To avoid the loss of hydrogen during the coating process, a low melting temperature eutectic Bi–Sn–In alloy was selected as a metal binder. The coated particles were used to build a packed bed regenerator as an array of fixed particles, avoiding such negative effects as sedimentation, segregation, and channel deformation. Similarity theory, combined with unsteady heat transfer approach was applied in order to calculate the optimal operation frequency and to estimate the maximal cooling power of the magnetocaloric regenerators. Two different geometries of heat exchangers were theoretically compared: stacked flat plate/channel structure and packed bed of equidimensional spherical particles. It is shown that, operating at low frequency, the same amount of magnetocaloric material can expel bigger amount of heat, when formed as packed bed heat exchangers. The metal-bonded packed bed regenerator made from La(Fe,Mn,Si)13H x powder was tested in a home-build versatile testing device in a magnetic field change of 10 kOe. The maximal achievable temperature span as a function of both parameters—hot end temperature and length of regenerator—was explored. The largest thermal span of 8 K was produced by the regenerator with 40 mm length.

The adiabatic temperature change $\Delta T_{\mathrm{ ad}}$ and the isothermal entropy change $\Delta S_{m}$ were measured in a Er2Fe14B single crystal in the temperature range of 250–370 K under a magnetic field change of $\Delta \mu _{0} H = 1.9$ T. The magnetic field was applied along the crystallographic axes $a$ and $c$ . Under adiabatic conditions, the application of a 0.5 T field along the $c$ -direction of the Er2Fe14B single crystal leads to a negative $\Delta T_{\mathrm{ ad}}$ at temperatures below the spin-reorientation temperature $T_{\mathrm{ SR}}=323$ K. In this case, the maximum $\Delta T_{\mathrm{ ad}}$ reaches −0.9 K in the temperature range of 270–280 K. Along the $a$ -direction, the magnetocaloric effect above $T_{\mathrm{ SR}}$ is positive, and $\Delta T_{\mathrm{ ad}}$ reaches 0.68 K in the magnetic field 0.5 T at the temperatures of 320–330 K. Under isothermal conditions, the maximal magnetic entropy change is −0.86 J kg $^{-1}\text{K}^{-1}$ at 328 K when the magnetic field is applied along the $a$ -direction and $\Delta S_{m}=1.27$ J kg $^{-1}\text{K}^{-1}$ at 275 K if the single crystal is magnetized along the $c$ -axis.

We report on magnetic properties of rare earth metals Nd and Sm after severe plastic deformation (SPD) by cold rolling. SPD considerably changes the magnetization behavior of both rare earth metals when measured along the rolling and out-of-plane sample directions. Specifically, a magnetic anisotropy, which is not due to the shape of the samples, originates from the texture and defects introduced by the SPD process.

Composite materials containing hydrogenated La(Fe,Mn,Si)13 powder and 5 wt.% of polymer binder have very good magnetocaloric properties and can be machined in a heat exchanger. These heat exchangers have to fulfill certain requirements regarding their mechanical and chemical stability. In this paper, we have investigated the magnetocaloric properties of thin composite plates produced by two different methods: 1) wire saw cutting and 2) cold rolling. The flexural strength of the plates was investigated by three-point bending method. Furthermore, the corrosive behavior of the plates in different heat transfer fluids was investigated. Finally, the adiabatic temperature change and the magnetic entropy change of the plates were observed over a seven-month period in order to evaluate their applicability in a real device.

Intrinsic magnetic properties of (Fe 1-xCo x) 2B (x = 0.20, 0.25, 0.30, 0.35) alloys have been studied on single crystals. Temperature dependence of both magnetocrystalline anisotropy constant K 1 and spontaneous magnetization M s has been determined from magnetization isotherms measured between 10 and 1000 K. The highest anisotropy constant K 1 was obtained at x = 0.25, K 1 = 494 kJ/m 3 at T = 10 K. The Curie temperature decreased from 966 to 930 K as x increased from 0.2 to 0.35.

We find a large Hall effect anisotropy in Y2Fe17-xCox single crystals with x les 2. The anomalous Hall effect resistivity rhoxy , obtained with an applied magnetic field H perpendicular to the c-axis, is almost one order of magnitude larger than the one for a magnetic field along c-axis (hard magnetization direction). rhoxy peaks close to the Curie temperature for both orientations. The variation of rhoxy with the longitudinal resistivity, in the zero magnetic field limit, shows that skew scattering dominates Hall resistivity for Hperpc whereas intrinsic Hall effect is important for H||c. This likely arises from a large planar anisotropy shown by these alloys.