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.

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.

scholarly journals Magnetic Properties of SmCo5 + 10 wt% Fe Exchange-Coupled Nanocomposites Produced from Recycled SmCo5

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1308 ◽  
Author(s):  
Arnab Chakraborty ◽  
Răzvan Hirian ◽  
Gregor Kapun ◽  
Viorel Pop
Keyword(s):  
Heat Treatment ◽  
Exchange Coupling ◽  
Permanent Magnets ◽  
High Energy ◽  
Raw Material ◽  
Energy Ball ◽  
Hydrogen Decrepitation ◽  
Energy Products ◽  
First Time ◽  
Recycled Material

Nanostructured alloy powders of SmCo5 + 10 wt% Fe obtained using recycled material were studied for the first time. The SmCo5 precursor was obtained from commercial magnets recycled by hydrogen decrepitation. The results were compared with identically processed samples obtained using virgin SmCo5 raw material. The samples were synthesized by dry high-energy ball-milling and subsequent heat treatment. Robust soft/hard exchange coupling was observed—with large coercivity, which is essential for commercial permanent magnets. The obtained energy products for the recycled material fall between 80% and 95% of those obtained when using virgin SmCo5, depending on milling and annealing times. These results further offer viability of recycling and sustainability in production. These powders and processes are therefore candidates for the next generation of specialized and nanostructured exchange-coupled bulk industrial magnets.

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.

scholarly journals Nanocrystalline Nd-Fe-B Alloys for Polymer-Bonded Magnets Production

2012 ◽  
Vol 2012 ◽  
pp. 1-6
Author(s):  
Aleksandar Grujić ◽  
Vladan Ćosović ◽  
Aleksandar Ćosović ◽  
Jasna Stajić-Trošić
Keyword(s):  
Magnetic Properties ◽  
Exchange Coupling ◽  
Magnetic Phase ◽  
Coupling Effect ◽  
Maximum Energy ◽  
Soft Magnetic ◽  
Nanocomposite Structure ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Composite Production

This study presents how different nanostructures of starting Nd-Fe-B particles have influence on magnetic properties of polymer-bonded Nd-Fe-B materials. Two types of nanocrystalline Nd-Fe-B alloys were used for polymer composite production by compression molding technique. The particles with low neodymium content (Nd-low) have nanocomposite structure with small exchange coupling effect between hard and soft magnetic phase. In other hand, practically monophase hard magnetic structure of Nd-Fe-B particles with stoichiometric neodymium content (Nd-stoich) shows improved magnetic properties. With increasing concentration of polymer matrix, the coercivity (Hcb), remanence (Br), and maximum energy product ((BH)max) decrease more prominenty for composites with stoichiometric Nd-Fe-B content.

scholarly journals Innovative processing routes in manufacturing of metal matrix composite materials

10.30544/629 ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 1-13
Author(s):  
Jovana Ruzic ◽  
Marko Simić ◽  
Nikolay Stoimenov ◽  
Dušan Božić ◽  
Jelena Stašić
Keyword(s):  
Ball Milling ◽  
Metal Matrix ◽  
Volume Fraction ◽  
Cost Effective ◽  
High Energy ◽  
High Energy Ball Milling ◽  
Processing Route ◽  
Ingot Metallurgy ◽  
Energy Ball ◽  
Manufacturing Techniques

Metal matrix composites (MMCs) belong to a group of modern materials owing to their excellent technological, mechanical, and physical properties such as excellent wear and corrosion resistance, high electrical and thermal conductivity, improved strength and hardness. Final properties of MMCs are affected equally by all steps of its manufacturing process. It is shown that by using adequate process parameters to obtain starting materials (reaching the specific size, shape, and reactivity) the control of volume fraction and distribution of reinforcements within the matrix can be achieved. For this purpose, mechanical alloying has been appointed as a good approach. MMCs can be produced using powder metallurgy, ingot metallurgy, and additive manufacturing techniques. Combining high-energy ball milling with these techniques enables the design of an innovative processing route for MMCs manufacturing. Mechanochemical process (achieved using high-energy ball milling) was employed in three manufacturing procedures: hot pressing, compocasting, and laser melting/sintering for obtaining of the suitable powder. These production routes for MMCs manufacturing were the subject of this work. The aim of MMCs design is to establish an optimal combination of production techniques merged into the cost-effective fabrication route for obtaining MMCs with required properties.

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.

Preparation and Magnetic Properties of the Exchange Coupling NdFeB Nanocomposited Permanent Magnets

2007 ◽  
Author(s):  
Zongjun Tian ◽  
Shangdong Li ◽  
Youwei Du ◽  
Yinhui Huang
Keyword(s):  
Magnetic Properties ◽  
Hysteresis Loop ◽  
Grain Boundaries ◽  
Exchange Coupling ◽  
Melt Spinning ◽  
Permanent Magnets ◽  
Energy Product ◽  
Remanence Ratio ◽  
Optimum Energy ◽  
Hard Magnetic Properties

The effect of indium additions on the microstructures and magnetic properties of Nd9Fe85−xB6Inx (x = 0–2) nanocomposites prepared by melt spinning was investigated. It was found that a certain amount of indium added to Nd9Fe85B6 magnets enhances the hard magnetic properties. The coercivity and remanence ratio of the magnet with 0.5 at.% indium increases from 405kA/m (no indium) to 465kA/m and from 0.7 to 0.86 respectively. Squareness of its hysteresis loop is also improved greatly. The optimum energy product (BH)max increases remarkably from 95kJ/m3 to 145kJ/m3. The origin for those enhancements is mainly attributed to the magnetically softened grain boundaries and enhanced crystallographical coherency by indium addition. The magnetic annealing is found to be helpful to enhance the coherency and coupling between hard and soft phases.

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.

Physical Metallurgy and Properties of β-solidifying TiAl Based Alloys

2011 ◽  
Vol 1295 ◽  
Author(s):  
Helmut Clemens ◽  
Thomas Schmoelzer ◽  
Martin Schloffer ◽  
Emanuel Schwaighofer ◽  
Svea Mayer ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Volume Fraction ◽  
High Energy ◽  
Heat Treatments ◽  
Hot Working ◽  
Physical Metallurgy ◽  
Compression Tests ◽  
Phase Volume Fraction ◽  
Β Phase

ABSTRACTIn this paper, the physical metallurgy and properties of a novel family of high-strength γ-TiAl-based alloys is reviewed succinctly. These so-called TNM™ alloys contain Nb and Mo additions in the range of 3 - 7 atomic percent as well as small additions of B and C. For the definition of the alloy composition thermodynamic calculations using the CALPHAD method were conducted. The predicted phase transformation and ordering temperatures were verified by differential scanning calorimetry and in situ high-energy X-ray diffraction. TNM alloys solidify via the β-phase and exhibit an adjustable β-phase volume fraction at temperatures, where hot-working processes are performed. Due to the high volume fraction of β-phase these alloys can be processed isothermally as well as under near conventional conditions. In order to study the occurring deformation and recrystallization processes during hot-working, in situ diffraction experiments were conducted during compression tests at elevated temperatures. With subsequent heat-treatments a significant reduction of the β-phase is achieved. These outstanding features of TNM alloys distinguish them from other TiAl alloys which must exclusively be processed under isothermal conditions and/or which always exhibit a high fraction of β-phase at service temperature. After hot-working and multi-step heat-treatments, these alloys show yield strength levels > 800 MPa at room temperature and also good creep resistance at elevated temperatures.

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