Explosive shock processing of Pr₂Fe₁₄B/α–Fe exchange-coupled nanocomposite bulk magnets

Abstract

Explosive shock compaction was used to consolidate powders obtained from melt-spun Pr 2 Fe 14 B/␣-Fe nanocomposite ribbons, to produce fully dense cylindrical compacts of 17-41-mm diameter and 120-mm length. Characterization of the compacts revealed refinement of the nanocomposite structure, with approximately 15 nm uniformly sized grains. The compact produced at a shock pressure of approximately 1 GPa maintained a high coercivity, and its remanent magnetization and maximum energy product were measured to be 0.98 T and 142 kJ/m 3 , respectively. The compact produced at 4-7 GPa showed a decrease in magnetic properties while that made at 12 GPa showed a magnetic softening behavior. However, in both of these cases, a smooth hysteresis loop implying exchange coupling and a coercivity of 533 kA/m were fully recovered after heat treatment. The results illustrate that the explosive compaction followed by post-shock heat treatment can be used to fabricate exchange-coupled nanocomposite bulk magnets with optimized magnetic properties.

Effect of Annealing, Stoichiometry, and Surface on Magnetism of (Pr,Dy)FeCoB Microparticles Ensemble

“…Similar spectra were observed for the (Pr,Dy) FeCoBZr alloys [12]. Few weak additional lines at 2Θ = 26° correspond to α-Fe [13]. Their contribution does not exceed 1 %.…”

Advances in nanostructured permanent magnets research

“…In rapid thermal compaction techniques including spark plasma sintering, shock compaction and explosive compaction, heating of samples can be controlled within a very short time while reaching a high pressure. Recently, bulk nanocomposite magnets have been prepared via spark plasma sintering and shock compaction by consolidation of nanoparticles and amorphous or nanocrystalline alloys powders [191][192][193][194][195][196]. These techniques have advantages of effectively restraining grain growth during the consolidation process and obtain high density fine grain materials in a short time [191,192].…”

“…Rong et al [192] reported compaction of 4 nm FePt/Fe 3 Pt with 70% density at 600 • C by the spark plasma sintering under the pressure of 100 MPa. It was found that the grain size of the sintered samples remains at the nanoscale after the post-annealing at 700 • C. Jin et al [196] produced bulk nanocomposite magnets with nearly full density by explosive compaction of melt-spun Pr 2 Fe 14 B/α-Fe nanocomposite ribbons. It was found that the explosive compaction resulted in the extensive deformation and introduction of microstructural defects such as twinning and dislocation generation.…”

Discrete particle simulation of shock wave propagation in a binary Ni+Al powder mixture

“…Granular compaction [1][2][3][4] is an important processing technique used to produce a variety of materials, including pharmaceutical tablets, 5 directionally aligned composite magnets, 6 and nanostructured high-strength metal parts. 7,8 Under dynamic shock-loading conditions, the process of granular compaction has been shown to initiate chemical reactions in reactive powder mixtures.…”