TbHo0.9−xNd0.1 (Fe0.8Co0.2)Sub>1.93 (0 ≤ x ≤ 0.40) particulate composites were prepared by embedding and aligning alloy particles in an epoxy matrix with and without a magnetic curing field. The magnetoelastic properties were investigated as functions of composition, particle volume fraction and macroscopic structure of the composite. The magnetic anisotropy compensation point was found to be around x = 0.25, where the easy magnetization direction (EMD) at room temperature was detected lying along ⟨ 1 1 1 ⟩ axis. The composite with ⟨ 1 1 1 ⟩ preferred orientation and pseudo-1-3 type structure was prepared under an applied magnetic field of 12 kOe. An enhanced magnetoelastic effect and large low-field magnetostriction λa, as high as 430 ppm at 3 kOe, were obtained for Tb0.25Ho0.65 Nd0.1 (Fe0.8Co0.2)1.93composite rod. The value of λa was of 72 % of its polycrystalline alloy (~595 ppm/3 kOe) although it only contained 30 vol.% of the alloy particles. This enhanced effect can be attributed to the larger λ111 (as compared to λ100), low magnetic anisotropy, easy magnetization direction (EMD) along the ⟨ 1 1 1 ⟩ axis and ⟨ 1 1 1 ⟩-textured orientation of the alloy particles as well as the chain-like structure of the composite. The good magnetoelastic properties of the composite, in spite of the fact that it contained only 30 vol.% of the alloy particles with light rare-earth Nd element in the insulating epoxy, would make it a potential material for magnetostriction application.
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Purpose: The aim of this work is to obtain polyurethane matrix composite materials reinforced by Tb0.3Dy0.7Fe1.9particles and to observe changes of magnetic properties and magnetostriction of samples with different particle size distributions of Tb0.3Dy0.7Fe1.9 powder. Design/methodology/approach: Polyurethane matrix composite materials reinforced by Tb0.3Dy0.7Fe1.9 magnetostrictive particles fabricating method were developed during the investigations, making possible to obtain materials with good physical properties. The influence of the concentration and powder particles size of the Td0.3Dy0.7Fe1.9 on magnetic and magnetostrictive properties were estimated. Metallographic examination of powders morphology and the structure observations of composite materials were made. Findings: Composite materials consisting of Td0.3Dy0.7Fe1.9 particles can extend the possibilities of application the magnetostrictive materials and reduce the cost of their manufacturing. The obtained materials show regular distribution of Td0.3Dy0.7Fe1.9 powder in polyurethane matrix. Research limitations/implications: The advantage of polyurethane matrix magnetostrictive composite materials are their simple technology and lowering manufacturing cost in comparison to monolithic Td0.3Dy0.7Fe1.9. These efforts can be considered as very up-to-date from the scientific point of view. Originality/value: The originality of this investigations is the statement that increasing the size of the Td0.3Dy0.7Fe1.9 particles cause increasing the strain response and this is due to the demagnetization effects.
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Purpose: The goal of this work was to describe manufacturing process of polymer matrix composite materials reinforced by Tb0.3Dy0.7Fe1.9 particles and to observe changes of physical properties (magnetic properties and magnetostriction) of samples with randomly oriented magnetostrictive particles in epoxy matrix and with aligning these particles in the matrix during fabrication process. Design/methodology/approach: Polymer matrix composite materials reinforced by the Tb0.3Dy0.7Fe1.9 magnetostrictive particles fabricating method was developed during the investigations, making it possible to obtain materials with good physical properties. The influence of the concentration of the Td0.3Dy0.7Fe1.9 particles on magnetic and magnetostrictive properties was estimated. Metallographic examination of powder’s morphology as well as EDS and XRD analysis and observations the structure of composite materials were made. Findings: The influence of magnetic particle alignment is observed in the magnetic and magnetostriction responses. The magnetostrictive response improves when the magnetic particles are oriented in magnetic fields and reaches approximately 184 ppm for oriented composite materials with 25% volume fraction of Td0.3Dy0.7Fe1.9 particles. Practical implications: For potential applications in technological devices, such as sensors and actuators, it is desirable to form composite systems by combining magnetostrictive phases with matrix, in order to have giant magnetostrictive effect and, at the same time, to reduce disadvantages of monolithic material. Originality/value: The originality of this work is based on manufacturing process, especially of applying magnetic alignment for ordering Td0.3Dy0.7Fe1.9 particles during polymerization of epoxy matrix.
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