Presentation Information
[P1-8]Hysteretic properties of (Nd,Ce,Tb)-(Fe,Co)-(Al,Cu,Ti)-B permanent magnets prepared by in-situ grain boundary diffusion
*Pavel Alexandrovich Prokofev1, Natalia Borisovna Kolchugina1, Nickolay Andreevich Dormidontov1, Nickolay Vladimirovich Kudrevatykh2, Anna Sregeevna Bakulina1, Mark Vladimirovich Zheleznyi1 (1. Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences (Russia), 2. Ural Federal University named after the First President of the Russian Federation B. N. Yeltsin (Russia))
Keywords:
Permanent magnet,rare earth alloy,hysteretic properties
Preparing the Ce–containing Nd–Fe–B hard magnetic materials exhibiting both a high coercive field and a high magnetic energy product is a great challenge. As is known, there is an overstocking of the Ce element, since the Ce2Fe14B compound is inferior in magnetization, anisotropy field and Curie temperature to the R2Fe14B compounds with R = Nd, Pr, Tb, Dy, which are currently characterized by the greatest use. In order to balance the utilization of rare–earth resources, researchers have partially replaced Pr and Nd with Ce to produce sintered magnets. Such a substitution requires the addition of a heavy rare-earth metal to improve the coercivity of sintered magnet.A hydrogenated Tb-Co-Cu-Hx intermetallic compound was used as the diffusion source to fulfill the in-situ grain-boundary diffusion and grain–boundary structuring of sintered magnet containing ∼8 wt% Ce. In this case, the (Nd,Ce)2Fe14B main phase grains with the Tb–diffusion shell (determined by scanning electron microscopy in using a wave detector) are formed in the sintered RE–Fe–B magnets (see Fig. 1).
The introduction of terbium and cobalt into the main–phase grain via the grain–boundary diffusion and copper accumulation at a triple junction were found. The precise in–situ engineering of the microstructure of permanent magnets is the method which allowed us to fabricate Nd–Ce–Fe–B magnets, in the case of resource–saving substitution of Ce for Nd, with the high hysteretic properties via the formation of core–shell grain structure giving the local increase in the magnetic anisotropy of the Ce–containing 2–14–1 phase.The degree of texture of the Ce–containing sintered magnet was estimated based on measurements of the remanence along and across the magnet texture; it is ∼0.96. The measurement of the field dependences of magnetization showed that the anisotropy field of the hard-magnetic Nd(Ce)2Fe14B phase at 50, 75, 125, and 150 ℃ is 52.7, 49.9, 37.5, and 33.5 kOe, respectively; the values are close to those of the Ce–free main magnetic phase. The hysteretic properties of the magnet measured at (1) 25, (2) 50, (3) 75, (4) 100, (5) 125, (6) 158, (7) 175, and (8) 200 ℃ are given in Table 1.
The temperature coefficients of remanence α and coercive force in magnetization β for the Ce–containing sintered magnet prepared with 4 wt % Tb–Co–Cu–Hx are given in Table 2.
This study provides an experiment basis for manufacturing high-coercivity Nd–Ce–Fe–B magnets by in-situ diffusing Tb–Co–Cu material in industry. The experimental results obtained indicate the possibility of the use of Ce–containing permanent magnets low–alloyed with Tb for creating various electronic devices.The study was performed in terms of state assignments nos. № 075-00320-2400 and FEUZ 2023-0020 and in part supported by State Corporation ROSATOM, state contracts nos. N.4shch.241.09.21.1101 and N.4shch.241.09.22.1141.
The introduction of terbium and cobalt into the main–phase grain via the grain–boundary diffusion and copper accumulation at a triple junction were found. The precise in–situ engineering of the microstructure of permanent magnets is the method which allowed us to fabricate Nd–Ce–Fe–B magnets, in the case of resource–saving substitution of Ce for Nd, with the high hysteretic properties via the formation of core–shell grain structure giving the local increase in the magnetic anisotropy of the Ce–containing 2–14–1 phase.The degree of texture of the Ce–containing sintered magnet was estimated based on measurements of the remanence along and across the magnet texture; it is ∼0.96. The measurement of the field dependences of magnetization showed that the anisotropy field of the hard-magnetic Nd(Ce)2Fe14B phase at 50, 75, 125, and 150 ℃ is 52.7, 49.9, 37.5, and 33.5 kOe, respectively; the values are close to those of the Ce–free main magnetic phase. The hysteretic properties of the magnet measured at (1) 25, (2) 50, (3) 75, (4) 100, (5) 125, (6) 158, (7) 175, and (8) 200 ℃ are given in Table 1.
The temperature coefficients of remanence α and coercive force in magnetization β for the Ce–containing sintered magnet prepared with 4 wt % Tb–Co–Cu–Hx are given in Table 2.
This study provides an experiment basis for manufacturing high-coercivity Nd–Ce–Fe–B magnets by in-situ diffusing Tb–Co–Cu material in industry. The experimental results obtained indicate the possibility of the use of Ce–containing permanent magnets low–alloyed with Tb for creating various electronic devices.The study was performed in terms of state assignments nos. № 075-00320-2400 and FEUZ 2023-0020 and in part supported by State Corporation ROSATOM, state contracts nos. N.4shch.241.09.21.1101 and N.4shch.241.09.22.1141.
