High-performance α-Fe/Pr2Fe14B-type nanocomposite magnets produced by hot compaction under high pressure

Abstract

The α-Fe/R2Fe14B-type nanocomposite magnets have been prepared by hot pressing melt spun Pr8Dy1Fe74.5Co10Nb0.5B6 flakes under a conventional pressure P of 125 MPa and high pressures ranging from 1 to 7 GPa. It was found that increasing compaction pressure from 125 MPa to 5 GPa led to marked grain refinement in the magnet and consequently resulted in significant improvement of magnetic properties. When hot pressing under even higher pressure (P>5 GPa), however, the crystallization was constrained and the hot pressed magnets retained a certain amount of amorphous phase besides the Pr2Fe14B-type phase and α-(FeCo) phase, which resulted in the deterioration of the magnetic properties. A remanence of 11.1 kG, coercivity of 10.2 kOe, and maximum energy product of 23.6 MGOe have been achieved in the magnet hot pressed under a pressure of 5 GPa.

Structure, thermal stability and magnetostrictive properties of PrFex (1.5≤x≤3.0) alloys

“…The sample shows a large magnetostriction λ || − λ ⊥ = 900 × 10 −6 at 13 kOe even the Fe content increases to x = 3.0. As we know, the high-pressure technique is also an effect method to fabricate nanocrystalline and nanocomposite system [11], it is hopeful that PrFe 1.9 /␣-Fe nanocrystalline can be prepared by combining melt-spinnng and high-pressure technique and the magnetostriction of the nanocrystalline Pr-Fe alloys at low magnetic fields is hopeful The CS, linewidth are given in mm/s, H hf is given in T, V zz is given in 10 21 V/m 2 , CS is relative the spectrum center of ␣-Fe. to be improved.…”

Effect of Ga addition on the magnetic properties and microstructure of nanocrystalline Nd12.3Fe81.7B6.0 ribbons

“…Although the grain size of nanocomposite magnets can be governed by using some special ways such as hot compaction under high pressure [10] or heat treatment in an external electric field [11][12], the process is time and energy consuming. It is verified that elemental additions are an easy and effective way to optimize the nano-structure, and hence result in a significant remanence enhancement and high performance [13][14][15][16][17].…”

Significant changes in the microstructure, phase transformation and magnetic properties of (Nd,Pr)2Fe14B/α-Fe magnets induced by Nb and Zr additions

“…Experimental results [1][2][3][4] and micromagnetic calculations [5][6][7] from numerous studies show that the magnetic properties of nanocomposite magnets are strongly dependent on the phase composition, the intrinsic properties and the grain sizes of the magnetic phases. Some special methods, such as hot compaction under high pressure [8] or heat treatment in a magnetic field [9], and elemental additions, such as Ga [10], Co [11] and Tb [12] were used to improve the magnetic properties by optimizing the microstructure, refining the grain size and increasing the intrinsic magnetic properties of magnetic phases. The usual way of preparing the Nd 2 Fe 14 B/␣-Fe nanocomposite is through the crystallization of amorphous phase into a mixture of hard and soft phases.…”