Advances in Magnetic Materials: High Energy Product Permanent Magnets
Sponsored by: TMS Functional Materials Division, TMS: Magnetic Materials Committee
Program Organizers: Jose Maria Porro, BCMaterials; Huseyin Ucar, California Polytechnic University,Pomona; Patrick Shamberger, Texas A&M University; Min Zou, Lab Magnetics, A Quadrant Company; Gaoyuan Ouyang, Ames Laboratory; Alex Leary, NASA Glenn Research Center
Tuesday 2:30 PM
March 21, 2023
Room: 33A
Location: SDCC
Session Chair: Gaoyuan Ouyang, Ames Laboratory
2:30 PM Invited
A Semi-continuous Hot Deformation Method for Making Anisotropic Nd-Fe-B Magnet: Chaochao Pan1; Gaoyuan Ouyang2; Wei Tang2; Jun Cui1; 1Iowa State University; 2Ames Laboratory
Nd-Fe-B (Neo) based magnet plays a dominant role in energy efficiency and renewable energy applications. However, Neo magnets need the critical heavy rare earth elements to function at higher temperature. Hot-deformed nanocrystalline anisotropic Neo magnets may attain high coercivity due to their highly orientated nano scale grains. However, making hot-deformed nanograin magnet requires a two-steps process: hot-press for densification followed by hot-deformation for texture. It is an inherently expensive process with limited productivity. Here, we report a novel nanograin Neo magnet fabrication method that is continuous and near-net-shape. We showed that cold roll of hot tube at 800°C with 70% thickness reduction can result in nearly full density anisotropic magnet with good BHmax 31.6 MGOe. Moreover, the method allows the making of continuous strip magnet that can be curved to match motor radius, making it possible to maximize the magnetic flux density on rotor circumference, thereby increase motor powder density.
3:00 PM
Increased Energy Product of Nd2Fe14B-based Magnets Processed by Concurrent HDDR within Applied Magnetic Fields: Zachary Tener1; Xubo Liu2; Ikenna Nlebedim2; Matthew Kramer2; Michael McGuire1; Michael Kesler1; 1Oak Ridge National Laboratory; 2Ames Laboratory
Thermo-Magnetic Processing (TMP) - HDDR (hydrogenation, disproportionation, desorption, recombination), or HDDR within an applied magnetic field, can produce anisotropic Nd2Fe14B powders with improved magnetic properties using drop-cast Nd-Fe-B alloy as feedstock. We investigate the effectiveness of TMP-HDDR in 0, 0.5, and 1 Tesla fields and a controlled H2 environment on drop-cast and commercially-attained sintered Nd2Fe14B magnets, and compare the resulting properties. Samples were characterized using X-ray diffraction, magnetometry, and electron microscopy to differentiate between TMP-HDDR on commercial samples versus those synthesized in the lab.This work is supported by the Critical Materials Institute, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office.
3:20 PM
Investigations into the Processing and Magnetic Properties of Nd-Fe-B Magnets Produced by Extrusion: Alexander Ruediger1; Sven Gall2; Sören Müller1; 1Extrusion Research and Development Center FZS, Technische Universität Berlin; 2INGWERK GmbH
Crystallographically and magnetically textured but dimensionally limited Nd-Fe-B permanent magnets fabricated by hot forming processes such as die-upsetting and backward extrusion have been extensively explored in the past.In contrast, the possibility of producing long magnetic profiles by extrusion has hardly been investigated. For this purpose, tools were designed which enable the processing of the common isotropic Nd-Fe-B powders produced in the melt spinning process in the loose, encapsulated and in the already hot-compacted, unencapsulated form. In both process variants, the powders were extruded into round profiles, whereby the extrusion temperature, ratio and speed were varied for the tests. This showed that Nd-Fe-B magnet material could be processed by extrusion using the chosen tool designs. In further experiments, the properties of the produced profiles were analyzed, and a magnetic anisotropy typical for hot forming of Nd-Fe-B material was also found for the extrusion process.
3:40 PM Cancelled
On Dysprosium Utilisation in Multi-main-phase Nd–Dy–Fe–B Magnets with Core–shell Microstructures: Hansheng Chen1; Zhiheng Zhang2; Jiaying Jin2; Xiaolian Liu3; Wei Li4; Mi Yan2; Simon Ringer1; 1The University of Sydney; 2Zhejiang University; 3Hangzhou Dianzi University; 4Nanchang Hangkong University
The development of high-performance Nd–Dy–Fe–B magnets that minimise the consumption of the relative scarce rare earth element Dy has been a major pursuit for both industry and academia in recent years. Here, we demonstrate a breakthrough in designing a series of Nd–Dy–Fe–B magnets that harness the liquid-phase sintering of the Dy-free and Dy-rich magnetic powders to form core–shell microstructures and achieve a high coercivity with little diminishment in the remanent magnetisation and maximum energy product. We propose a two-step mechanism comprising solid-state-diffusion and solution reprecipitation to explain the formation of the core–shell microstructures. Using advanced multi-scale microscopy and microanalysis, together with micromagnetic simulations, we reveal the influence of the core–shell microstructures on the evolution of the magnetic domains and the magnetic properties. The present work establishes a pathway for the more sustainable utilisation of Dy in permanent magnets via forming the uniform core–shell microstructures.
4:00 PM Break
4:15 PM
Hard Magnetic SmCo5-Cu Nanocomposites Produced by Severe Plastic Deformation: Franziska Staab1; Enrico Bruder1; Karsten Durst1; 1Technical University Darmstadt
Textured nanocrystalline SmCo5-Cu magnets are produced by high-pressure torsion (HPT) of powder blends consisting of SmCo5 and Cu powder. The process enables a free selection of the magnetic phase and the grain boundary phase and overcomes limitations imposed by the phase diagram as in conventional sintering routes. With increasing number of rotations, a structural refinement, and an increasing coercivity are observed. TEM and EBSD analyses reveal fragmentation via particle fracture and plastic deformation as microstructural refinement processes. The magnetic hardening is ascribed to the microstructural refinement and the magnetic decoupling of the hard magnetic SmCo5 grains by Cu. The microstructural analyses and magnetic hysteresis measurements indicate the formation of a texture during the HPT process. Consequently, the work demonstrates a new approach for the generation of textured nanostructured hard magnets.
4:35 PM
Influence of Severe Plastic Deformation on the Magnetic Properties of SmCo Permanent Magnets: Alexander Paulischin1; Lukas Weissitsch1; Stefan Wurster1; Heinz Krenn2; Reinhard Pippan1; Andrea Bachmaier1; 1Erich Schmid Institute of Materials Science of the Austrian Academy of Sciences; 2Institute of Physics, University of Graz
The increasing global energy consumption over the past decade lead to a rising demand on high performance permanent magnets (PMs). These PMs, which are based on combinations of rare earths and transition metals, are commonly produced by conventional powder-metallurgical techniques such as milling, pressing and sintering. In this study a novel approach to process PMs based on different SmCo phases is presented by using high pressure torsion (HPT), a method of severe plastic deformation. SmCo powders are compacted in Ar atmosphere to prevent oxidation and subsequently HPT-deformed, resulting in dense bulk specimens with an ultrafine grained microstructure. The respective microstructures depend on the chosen deformation parameters (e.g. deformation temperature, applied strain) and are characterized using scanning electron microscopy as well as X-ray diffraction techniques. Magnetic properties are measured by SQUID magnetometry and the results show a strong correlation between the magnetic properties and the applied amount of deformation.
4:55 PM
Toughening Sm-Co Sintered Magnets by Additive-modified Microstructure Engineering: Baozhi Cui1; Xubo Liu1; Cajetan Ikenna Nlebedim1; Jun Cui1; 1Ames Laboratory
Samarium-cobalt (Sm-Co) sintered magnets have high magnetic energy densities, great resistance to demagnetization and corrosion, and excellent thermal stability. However, the utilization of these magnets is restricted by their brittleness. Based on the micromechanical and the Zener pinning model, Sm-Co sintered magnets with improved mechanical properties have been designed and fabricated via an additive-modified microstructure engineering. A small amount of fine Sm2O3 particulates has been incorporated into Sm2(CoFeCuZr)17 sintered magnets to refine the grain size by up to approximately 50% and narrow the grain size distribution. Doping with 3 wt% Sm2O3 increased the flexural strength by 62% while maintaining magnetic performance. Micromechanical simulation indicates that the fracture is dominated by intragranular mode. The mechanical strength is mainly enhanced by the additive-induced grain refinement, while the small amount of Sm2O3 addition has little direct effect on mechanical properties. These magnets will be more cost-effective, efficient, and robust for various functional applications.