hot / hot deformation Nd_2 (FeCo) _14B/α- (FeCo) magnetic materials, microstructure and magnetic properties of

Title: hot / hot deformation Nd_2 (FeCo) _14B/α- (FeCo) magnetic materials, microstructure and magnetic properties of
　　Author: Zhang Wenwang
　　Degree-granting units: Ningbo University
　　Keywords: hot / hot deformation magnet;; Co added;; crystallization;; microstructure;; magnetic
　　Summary:
　　Nanocomposite rare earth permanent magnet material with excellent magnetic potential, the theoretical energy product is about the industrialization of the now twice as sintered NdFeB magnets, and its rare earth content is low, cheap, promise to become a Magnetic lifter new generation of permanent magnetic materials.
　　In this paper, hot melt-quenching and / prepared by hot deformation process Nd_2Fe_ (14) B / α-Fe-type rare earth permanent magnet materials, through the use of X-ray diffraction (XRD), differential scanning calorimetry analyzer (DSC ), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), an integrated physical properties measurement system (PPMS) and other analytical instruments and methods, analysis of Co element for non Jingjing process effects of Co element to add volume and deformation temperature of the alloy microstructure and magnetic properties, and by analyzing the δM (H) curve and the curve of the irreversible magnetic susceptibility of the alloy to intergranular interactions. 35m / s speed roll prepared under Nd_9Fe_ (85.5-x) Co_xB_ (5.5) (x = 0,1,3,5) by the melt-spun ribbons mainly composed of amorphous, contains only a small amount of α-Fe/α- (FeCo ) phase and Nd_2Fe_ (14) B/Nd_2 (FeCo) _ (14) B phase; In addition, Nd_9Fe_ (85.5-x) Co_xB_ (5.5) B (x = 5) melt-spun ribbon also contains Nd_3 ( FeCo) _ (62) B_ (14) metastable phase. As the Co element into the soft and hard magnetic phase, Nd_9Fe_ (80.5) Co_5B_ (5.5) B (x = 5) strip of soft and hard magnetic phase of the Curie temperature were increased, never Co alloy of 770 ℃ and 370 ℃ respectively. increased to 850 ℃ and 395 ℃. Due to the lack of rare earth-rich phase, Nd_9Fe_ (80.5) Co_5B_ (5.5) (x = 1,5) is not dense hot magnet (about 7.0g/cm3). From 1at% Co content increased to 5at%, magnet weakened intergranular exchange coupling, the coercivity and maximum energy product increased slightly. Co add significantly reduces Nd_9Fe_ (85.5-x) Co_xB_ (5.5) (x = 0,1,3,5) the grain size of the magnet thermal deformation, add 1at% Co, the soft phase-and 2:14:1 phase were never average grain size of Co alloy 61nm, 168nm reduced to 24nm, 50nm, but added 5at% Co, because there is a thin band of Nd_3 (FeCo) _ (62) B_ (14) B metastable phase decomposition at higher temperatures, two-phase average grain size are increased slightly. As the composition and microstructure of different materials with increasing Co content the coercivity increases monotonically. From the composition analysis, Co increases will produce more with lower magnetic anisotropy constant of Nd_2 (FeCo) _ (14) B phase, the coercivity has weakened the role. We analyze the magnet δM (H) curve found no Co alloy grains to long-range magnetostatic coupling-based, add short-range exchange coupling in Co alloys the main role, add 5at% Co, due to increased grain size large, short-range exchange coupling weakens, which explains the Co content increases with increase in coercivity reasons. Because of interactions between materials and the crystalline microstructure of the material are closely related, so that, compared with the alloy composition, microstructure of the material coercivity greater impact. Deformation temperature increases from 1143K to 1203K, Nd_9Fe_ (80.5) Co_5B_ (5.5) heat distortion magnet Nd_2 (FeCo) _ (14) B phase, the average grain size increased from 70nm to 90nm. As the impact of the microstructure, deformation temperature increases from 1143K to 1203K, the material remanence, coercivity and maximum energy product decreased, respectively, from 0.67T, 218 kA / m and 40.9 kJ / m reduced to 0.56T, 158 kA / m and 25.9 kJ / m. Analysis of materials 3δM (H) curve and irreversible susceptibility curves were found, 1143K heat distortion magnets mainly intergranular exchange coupling, while the 1203K heat distortion http://www.999magnet.com/products/131-magnetic-lifter magnets for long-range magnetostatic coupling-based, which explains the 1143K heat distortion magnet reasons for the higher coercivity.
　　Nd_9Fe_ (84.5-x) Co_xB_ (5.5) (x = 1,3, and 5) heat distortion appears weak magnet [410] texture, the apparent degree of texture with deformation temperature and Co content have a relationship. 1203K than 1143K thermal deformation magnet magnet has a higher heat distortion [410] crystal orientation to the degree; Co content increased from 1at% to 5at%, c-axis preferred orientation of the magnet increased.
　　Degree Year: 2010