Effect of microstructure parameter on the energy product in two-phase permanent magnetic materials

2019 ◽  
Vol 33 (03) ◽  
pp. 1950025
Author(s):  
Reshma Reba Alexander ◽  
R. Justin Joseyphus
Keyword(s):  
Magnetic Materials ◽  
Permanent Magnets ◽  
High Energy ◽  
Microstructural Parameter ◽  
Two Phase ◽  
Magnetic Phases ◽  
Microstructure Parameter ◽  
Energy Product ◽  
Effect Of Microstructure

Two-phase permanent magnets with soft and hard magnetic phases are suitable candidates for high energy product permanent magnets. To obtain enhanced energy product, the microstructure has to be optimum and the magnetization and nucleation field has to be as large as possible. The present studies suggest suitable combinations of soft–hard composites that could result in higher energy product. The role of microstructural parameter on the energy product is also presented.

High Coercivity Mechanism Of The Die-Upset Hard Magnets Re13.75Fe80.25B6 (Re = Nd, Pr): Possible Correlation To Specific DefectMicrostructure

1999 ◽  
Vol 5 (S2) ◽  
pp. 42-43
Author(s):  
V.V. Volkov ◽  
Y. Zhu
Keyword(s):  
Magnetic Structure ◽  
Permanent Magnets ◽  
Materials Science ◽  
High Energy ◽  
High Coercivity ◽  
Energy Product ◽  
Hard Magnets ◽  
Energy Products ◽  
Processing Techniques

The magnetic properties of permanent magnets are sensitive to their microstructure. In particular, for the family of Nd(Pr)-Fe-B magnets a very different coercivity and energy products may be obtained by several processing techniques. It was experimentally found that a small excess of Nd over the exact phase composition of Nd2Fe14B plays an important role in obtaining high-energy products during the die-upset processing of the anisotropic hard magnets. However the specific role of the Nd excess on both magnetic structure and microstructure of these die-upset magnets is unclear and controversial. Answers to these questions may help to correctly address some major issues in materials science, e.g. how microstructure is related to magnetic structure of hard magnets, and how to optimize the performance of hard magnets.In-situ TEM magnetizing experiments combined with Lorentz magnetic microscopy in Fresnel-Foucault modes were used to characterize the magnetic structure of die-upset, high energy-product hard magnets Nd13.75Fe80.25B6 and Pr13.75Fe80.25B6.

A Comparative Study between Low and High-Energy Milling Processes for the Production of HD PrFeCoBNb Sintered Magnets

2008 ◽  
Vol 591-593 ◽  
pp. 114-119 ◽  
Author(s):  
E.A. Périgo ◽  
E.P. Soares ◽  
Hidetoshi Takiishi ◽  
C.C. Motta ◽  
Rubens Nunes de Faria Jr.
Keyword(s):  
Ball Milling ◽  
Permanent Magnets ◽  
High Energy ◽  
Maximum Energy ◽  
Maximum Energy Product ◽  
High Energy Milling ◽  
Energy Product ◽  
Energy Processing ◽  
Hydrogen Decrepitation ◽  
High Degree

Roller-ball milling (RBM) or planetary ball milling (PBM) have been used together with the hydrogen decrepitation (HD) process to produce sintered permanent magnets based on a mixture of Pr16Fe76B8 and Pr14.00Fe63.90Co16.00B6.00Nb0.10 magnetic alloys. Five distinct compositions have been studied comparing low- and high-energy milling. Magnets with a particular composition and prepared using these two routes exhibited similar magnetic properties. Modifications have been carried out in the procedure of the HD stage for PBM in order to guarantee a high degree of crystallographic alignment. Pr15.00Fe69.95Co8.00B7.00Nb0.05 magnets showed the best maximum energy product for both processing routes (~ 247 kJm-3). A significant reduction in the milling time (93%) has been achieved with high-energy processing, the greatest advantage over the low-energy route.

NdFeB/αFe Nanocomposite Permanent Magnets with Enhanced Properties Prepared by Spark Plasma Sintering

2011 ◽  
Vol 672 ◽  
pp. 229-232
Author(s):  
Marian Grigoraş ◽  
M. Lostun ◽  
Nicoleta Lupu ◽  
Horia Chiriac
Keyword(s):  
Spark Plasma Sintering ◽  
Permanent Magnets ◽  
High Energy ◽  
Maximum Energy ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Ball ◽  
Melt Spun Ribbons

Nanocomposite NdFeB/αFe magnets were obtained by spark plasma sintering technique using high energy ball-milled Nd-Fe-B melt-spun ribbons mixed in different weight ratios with Fe commercial powders. The remanence of SPS nanocomposite magnets increases with the Fe powders content from 6.1 for 4 wt.% Fe to 6.4 kG for 5 wt.% Fe, while the estimated maximum energy product is also increased from 9.0 to 10.6 MGOe.

Study on the Nanostructure and Magnetic Properties of NdFeNbB Permanent Magnets

2010 ◽  
Vol 638-642 ◽  
pp. 1749-1754
Author(s):  
X.F. Wang ◽  
X.Y. Chen ◽  
Z.L. Jiang ◽  
Y. Chen ◽  
H.M. Chen
Keyword(s):  
Exchange Coupling ◽  
Permanent Magnets ◽  
Coupling Effect ◽  
Maximum Energy ◽  
Soft Magnetic ◽  
Magnetic Phases ◽  
Maximum Energy Product ◽  
Energy Product ◽  
High Maximum ◽  
Intrinsic Coercivity

Nd2Fe14B/-Fe nanocomposite permanent magnet contains the hard and soft magnetic phases, Nd2Fe14B and -Fe respectively. An exchange coupling effect exists between the two magnetic phases. The effect of alloying element Nb on its nanostructure and properties have been studied. Adding Nb to the alloy is effective to refine grains, a relatively small grain size causes a high intrinsic coercivity, remanence and therefore a high maximum energy product, (BH)max. MFM (Magnetic Force Microscope) was used to observe the magnetic micro-domain structure in the nanophase alloys. The length of the magnetic contrast shows a significant dependence on the microstructure and phase constitution, and the longer length is correspond with the larger exchange coupling effect between the soft and hard magnetic phases.

High‐energy product Nd‐Fe‐B permanent magnets

1984 ◽  
Vol 44 (1) ◽  
pp. 148-149 ◽  
Author(s):  
J. J. Croat ◽  
J. F. Herbst ◽  
R. W. Lee ◽  
F. E. Pinkerton
Keyword(s):  
Permanent Magnets ◽  
High Energy ◽  
Energy Product

Rare-earth-free high energy product manganese-based magnetic materials

Nanoscale ◽  
2018 ◽  
Vol 10 (25) ◽  
pp. 11701-11718 ◽  
Author(s):  
Ketan Patel ◽  
Jingming Zhang ◽  
Shenqiang Ren
Keyword(s):  
Rare Earth ◽  
Magnetic Materials ◽  
Rare Earth Metal ◽  
Earth Metal ◽  
High Energy ◽  
Energy Product

The constant drive to replace rare-earth metal magnets has initiated great interest in an alternative.

scholarly journals High-energy product exchange-spring FePt/Fe cluster nanocomposite permanent magnets

2006 ◽  
Vol 305 (1) ◽  
pp. 76-82 ◽  
Author(s):  
X. Rui ◽  
J.E. Shield ◽  
Z. Sun ◽  
L. Yue ◽  
Y. Xu ◽  
...  
Keyword(s):  
Permanent Magnets ◽  
High Energy ◽  
Energy Product ◽  
Exchange Spring

scholarly journals Cluster-Assembled Iron-Platinum Nanocomposite Permanent Magnets

2006 ◽  
Vol 962 ◽  
Author(s):  
Xiangxin Rui ◽  
Zhiguang Sun ◽  
Yingfan Xu ◽  
David J. Sellmyer ◽  
Jeffrey E. Shield
Keyword(s):  
Exchange Coupling ◽  
Permanent Magnets ◽  
Volume Fraction ◽  
High Energy ◽  
Heat Treatments ◽  
Processing Route ◽  
Soft Magnetic ◽  
Soft Phase ◽  
Energy Product ◽  
Post Deposition

ABSTRACTExchange-spring nanocomposite permanent magnets have received a great deal of attention for their potential for improved the energy products. Predicted results, however, has been elusive. Optimal properties rely on a uniformly fine nanostructure. Particularly, the soft magnetic phase must be below approximately 10 nm to ensure complete exchange coupling. Inert gas condensation (IGC) is an ideal processing route to produce sub-10 nm clusters method. Two distinct nanostructures have been produced. In the first, Fe clusters were embedded in an FePt matrix by alternate deposition from two sources. Fe cluster content ranged from 0 to 30 volume percent. Post-deposition multi-step heat treatments converted the FePt from the A1 to L10 structure. An energy product of approximately 21 MGOe was achieved. Properties deteriorated rapidly at cluster concentrations above 14 volume due to uncoupled soft magnetic regions (from cluster-cluster contacts) and cooperative reversal. The second nanostructure, designed to overcome those disadvantages, involved intra-cluster structuring. Here, Fe-rich Fe-Pt clusters separated by C or SiO2 were fabricated. Phase separation into Fe3Pt and FePt and ordering was induced during post-deposition multi-step heat treatments. By confining the soft and hard phases to individual clusters, full exchange coupling was accomplished and cooperative reversal between clusters was effectively eliminated. An energy product of more than 25 MGOe was achieved, and the volume fraction of the soft phase was increased to greater than 0.5 while maintaining a coercivity of 6.5 kOe. The results provide new insight into developing high energy product nanostructured permanent magnets.

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