Study On Preparation, Structure And Magnetostriction Of High-Pr Content Alloys And Its Epoxy Composites

A series of Tb_0.2Pr_0.8(Fe_0.4Co_0.6)_1.87C_0.05B_0.01 （0≤x≤0.08） alloys were prepared by arc-melting,top casting method and subsequent annealing. XRD analysis show that a single cubic Laves phase forms in all alloys when x<0.06. The lattice parameter a, of the Laves phase in the studied alloys increase with increasing the boron content up to x=0.04, then decrease till x=0.08. Magnetic measurements indicate that the curie temperature, Tc , decreases slightly over a concentration range up to about x=0.06, followed by a strong decrease till x=0.08, Magnetic dilution of Co-sublattice /Fe-sublattice by the non-magnetic boron atoms result in a decrease of the saturation magnetization of Laves phase. The magnetic anisotropy constants K1 decrease with increasing the boron content when 0≤x≤0.03, then slightly increase with further increasing of x. The magnetostrictionλa = （λ/ /?λ⊥） of alloys initially increase with the boron content, reaching a maximum value at x=0.01, then decrease with increasing of the boron content. The spontaneous magnetostrictionλ111 decreases with increasing boron content. The results show that the Tb0.2Pr0.8（Fe0.4 Co0.6）1.87C0.05B0.01 alloy has a good magnetostriction at relatively low magnetic fields and a good application prospect.Different size of Tb_0.2Pr_0.8(Fe_0.4Co_0.6)_1.87C_0.05B_0.01 alloy powder were prepared by manual grinding. The composites samples were prepared by different preparation processes. The result shows that the magnetostrictionλa of cuboids samples with the particle size of 100～150um at the maximum available magnetic field of 13kOe with the same binder content 5% and model pressure 100MPa; The magnetostrictionλa of the cuboids samples is the maximum （λa=650ppm） at the magnetic field of 13kOe with the particle size of 100～150um, the binder content of 7%, and the model pressure of 150MPa; The density of the composites sample decrease with the increasing of the binder content and decreases with the increasing of the model pressure; The magnetostriction of composites with the magnetized powder and the same binder content decreases with the increasing of model pressure, and its magnetostriction at low magnetic field is superior than that of without magnetizing treatment composites. Orientation bonded epoxy composites were prepared by curing the binder under a moderate magnetic field. Structure analysis shows that the easy magnetization〈111〉of Tb_0.2Pr_0.8 (Fe_0.4Co_0.6)_1.87C_0.05B_0.01 alloys oriented along the direction of magnetic field and show an approximate chain structure with the curing magnetic field of 10KOe. The〈111〉Orientation of the composites samples with the binder content 50% increase with the increasing of orientation magnetic field up to 8KOe, then keep no change with the curing magnetic field further increasing. The〈111〉orientation of the composites samples with the same curing magnetic field 7.5KOe increase with the increasing of binder content up to 50%, then keep no change with the binder content further increasing. The magnetostriction of the orientation curing composites （cured at 10KOe for 2 hours） decrease with the binder content over the range of 12%～18%,then increase slightly when the binder content increase to 20%, the density of the composites sample decreases with the increasing of the binder contents. The magnetostriction of the composites rapid initially increases with the increasing curing magnetic field up to 7.5KOe, and then slight increases with it further increasing. The magnetostrictionλa of epoxy composite with the binder content of 20% and magnetic field of 10KOe at the maximum available magnetic field of 13 KOe is 412ppm and the desity is 4.39g/cm³. More particles are rotated in their eastiest magnetic direction with the increasing of curing time at 5h, which is benefit to improve the magnetostriction of composites. The results indicate that the epoxy composites curing under a moderate magnetic field exhibits low density and good magnetostriction property.