Microstructure and magnetostrictive properties of epoxy-bonded Tb_1-xNd_x(Fe_0.8Co_0.2)_1.93 (0.20 ≤ x ≤ 0.75) composites

Abstract

An epoxy-resin bonding route was used to produce composite rods of the highly magnetostrictive alloys Tb 1-x Nd x( Fe 0.8 Co 0.2)1.93 (0.20 ≤ x ≤ 0.75). The structure, spin configuration, magnetostriction and particle size are investigated by means of X-ray diffraction (XRD), a standard strain technique and scanning electron microscope (SEM). The epoxy-bonded 0–3 type and pseudo 1–3 type composites are successfully fabricated, respectively. XRD analysis shows that the easy magnetization direction (EMD) for the alloy of x = 0.20 lies along 〈111〉 axis. The magnetic curing field makes the particles align as a particulate chain and also causes the particles rotating along its EMD direction. The pseudo 1–3 type epoxy-bonded composite has a larger magnetostriction than that of the 0–3 type composite, which can be attributed to the larger magnetostriction coefficient λ111, EMD lying along 〈111〉 direction, the 〈111〉-textured orientation and the chain structure. A large saturation magnetostriction (λ0S ~ 570 ppm) is achieved for the 1–3 type epoxy/ Tb 0.35 Nd 0.65( Fe 0.8 Co 0.2)1.93 composite (about 150–250 μm, 10 kOe), which approaches 70% of its monolithic alloy. Furthermore, it only contains 27 vol.% alloy particles in the insulating epoxy matrix and performs a low magnetic anisotropy, which could make it technologically interesting for the field of Nd -containing magnetostrictive materials.

Magnetoelastic properties of epoxy resin based TbxHo0.9−xNd0.1 (Fe0.8Co0.2)1.93 particulate composites

“…6. The saturation linear anisotropic magnetostriction λ 0S was estimated by the law of approach to saturation as [11]:…”

“…As for the particulate composites, an epoxyresin bonding route has been used to produce rod samples [11]. Predetermined quantities of alloy particles and epoxy resin (Araldite LY1564/ Aradur 3487, tensile modulus of 3200 MPa to 3350 MPa) were homogeneously mixed in a plastic mold.…”

“…For comparison, the moulds were placed in an electromagnet for 8 hours for solidification. A uniform DC magnetic field of 12 kOe was provided along the longitudinal direction of the moulds, causing the particles to align with the direction of magnetic field and producing particulate chains similar to pseudo-fiber composites (classified as pseudo-1-3 type composites), in which the embedded alloy particle phase was connected in one direction and the second phase of epoxy matrix was connected in all three directions [7,11]. The particle volume fraction of the composite was determined based on Archimedes principle and the ruleof-mixture formulation for density as:…”

Dynamic magnetoelastic properties of TbxHo0.9−xNd0.1(Fe0.8Co0.2)1.93/epoxy composites

“…Subsequently, the ingots were ground into a particulate form with randomly distributed sizes in a range of about 75 µm to 150 µm. To prepare the particulate composites, an epoxy-resin bonding route was used to obtain rod samples [14]. Predetermined quantities of alloy particles and epoxy resin (Araldite LY5210/HY2954), corresponding to a particle volume fraction V f ∼ 0.3, were homogeneously mixed in a plastic mold.…”