Fabrication of bulk anisotropic Nd2Fe14B/α-Fe nanocomposite magnets with two-step high-pressure thermal compression

Achieving ultrastrong anisotropy in bulk Pr2Fe14B/α-Fe nanocomposite magnets by high-pressure thermal compression

“…The weight fraction of α-Fe phase is determined to be ∼ 29 wt.% and most Pr 2 Fe 14 B grains are aligned along its easy magnetisation axis (00 l) parallel to the pressure direction, which is indicated by the remarkably strengthened (004), (105), and (008) reflection peaks (Figure 1(a)), where the intensity ratio of I (004) /I (220) = 2053% (Figure 1(d)) is much larger than that (73%) of isotropic Pr 2 Fe 14 B crystals (see the Inorganic Crystal Structure Database (ICSD): 614150) (Figure 1(c)). Moreover, the I (004) /I (220) value of the produced sample is also much larger than that ( ∼ 631%) in our previous work [18]. This can be further confirmed by the significantly weakened (004), (105), and (008) reflection peaks (Figure 1(b)) on the surface parallel to the pressure direction, where the intensity ratio of I (004) /I (220) = 1.6% (Figure 1(e)) is much lower than that (73%) of isotropic Pr 2 Fe 14 B crystals.…”

“…The trade-off between the magnetic anisotropy and soft-phase fraction has always been a formidable challenge for the fabrication of highenergy-product bulk nanocomposite magnets [14,24]. Strikingly, the remanence ratio of (B r -B ⊥ r ) / B r with a value of ∼ 0.72 in this study is far away from the shaded region [3,8,[15][16][17][18][19][20][21][22][23][25][26][27][28][29] (as shown in Figure 4), indicating that a record-high magnetic anisotropy together with high soft-phase fraction has been obtained in bulk Pr 2 Fe 14 B/α-Fe nanocomposite magnet.…”

“…To quantify the degree of magnetic anisotropy, the remanence ratio of (B r -B ⊥ r ) / B r is generally employed. Numerous studies over the recent decades indicated that with increasing softphase fraction, the magnetic anisotropy and energy density of bulk nanocomposite magnets are greatly For comparison, the magnetic anisotropy of single-phase R-Fe-B and SmCo 5 magnets [8,20,21,25,26], SmCo/α-Fe(Co) magnets [3,8,15,28], multiphase hybrid magnets [16,17,29] and R 2 Fe 14 B/α-Fe magnets [18,19,23,27] reported in previous literatures together with the data in this work are presented. deteriorated [7,18,23].…”

“…Numerous studies over the recent decades indicated that with increasing softphase fraction, the magnetic anisotropy and energy density of bulk nanocomposite magnets are greatly For comparison, the magnetic anisotropy of single-phase R-Fe-B and SmCo 5 magnets [8,20,21,25,26], SmCo/α-Fe(Co) magnets [3,8,15,28], multiphase hybrid magnets [16,17,29] and R 2 Fe 14 B/α-Fe magnets [18,19,23,27] reported in previous literatures together with the data in this work are presented. deteriorated [7,18,23]. The trade-off between the magnetic anisotropy and soft-phase fraction has always been a formidable challenge for the fabrication of highenergy-product bulk nanocomposite magnets [14,24].…”

“…Although record-high energy products have been obtained, the degree of magnetic anisotropy with the value of 0.29 in SmCo/FeCo and 0.33 in NdFeB/Fe is still very poor as compared with that ( > 0.5) of conventional single-phase anisotropic rare-earth magnets [8,20]. Therefore, to further improve the energy products of bulk nanocomposite magnets, it is of great significance to strengthen the hard-phase texture [15,18,22].…”