Advanced Magnetic Materials for Energy and Power Conversion Applications: Advances in Characterization and Design of Emerging Permanent Magnetic Materials
Sponsored by: TMS Functional Materials Division, TMS: Magnetic Materials Committee
Program Organizers: Daniel Salazar, BCMaterials; Alex Leary, NASA Glenn Research Center; Markus Chmielus, University of Pittsburgh; Ryan Ott, Ames Laboratory; Arcady Zhukov, University of the Basque Country
Thursday 8:30 AM
February 27, 2020
Room: Del Mar
Location: Marriott Marquis Hotel
Session Chair: Konstantin Skokov, Technische Universität Darmstadt; Satoshi Hirosawa, National Institute for Materials Science
8:30 AM Invited
In-Situ and Ex-Situ Observations of Phase Selection in Magnet Alloys: Matthew Kramer1; A.C. Chaung2; Iver Anderson1; Pratik Ray3; E.M.H. White1; T. Prost1; E. Rinko1; 1Ames Laboratory; 2Argonne National Laboratory; 3Indian Institute of Technology Ropar
Magnetic alloys possess finely tuned nanostructures which balances phases selection, their grain size and orientation to optimize coercivity, magnetization and remanence. Determining how various processing parameters can effect an alloys’ phase selection and microstructure is paramount in order to optimize alloy design and its processing. Processing parameters are very sensitive to time-temperature conditions, so are not always reliably investigated by quenching and post-mortem analysis. High-energy synchrotron X-rays provide high fidelity time resolved (sub-second) small and wide-angle diffraction at temperature (RT – 1250C) to track the phase evolution at both isochronal and isothermal conditions provides unique insight into these temporal sensitive processes. We have analyzed Rare Earth (RE) and non- RE based magnet alloys processing using in situ methods. In particular, will relate the in situ characterization of the spinodal formation in the RE-free alnico alloys whose optimized magnetic properties are dependent of the appropriate time/temperature of the thermal magnetic annealing.
9:00 AM Invited
Optimizing the Magnetic Performance of Tetragonal ReFe12-xMx Phases using ab initio Computational Methods: Heike Herper1; Olga Vekilova1; 1Uppsala University
Predicting materials with tailored properties from computational simulations has become an inherent tool of materials design. To identify new rare-earth lean magnets the tetragonal 1:12 phase (35% less RE than commercial Nd-Fe-B magnets) was systematically investigated. Using ab initio methods, the change in the magnetic performance due to variation of the concentration of the RE and the phase stabilizer M were calculated to identify a “magnetic performance map”. The focus was on Sm- and Nd-based ReFe12-xMx. phases with M = Ti, V. For Nd1-xYxFe11-yTiy a large stable phase space was found with uniaxial anisotropy in the Ti-rich side. Including N to the picture the uniaxial anisotropy range is shifted to lower Ti concentrations especially for larger Y concentrations. With SmFe11V system a new phase was found leading to an increase of the magnetization by 17% compared to the commonly used concentrations of V [JALCOM 786, 969 (2019)].
9:30 AM
Cerium-based Gap Magnets Recent Advances in Understanding and Optimization: Andriy Palasyuk1; Savannah Downing2; Olena Palasyuk1; Tae-Hoon Kim1; Matthew Lynn1; Lin Zhou1; Matthew Kramer1; Sergey Bud'ko1; Paul Canfield1; 1Ames Laboratory; 2Iowa State University
Cerium-based permanent magnets, developed by the Critical Materials Institute (CMI), represent an alternative for supply dependent critical rare-earth (RE) magnets. They are process effective and less susceptible to supply disruptions. Our experiments show that these magnets easily achieve performance in the energy gap currently existing between low- and high-flux RE permanent magnets. Their unique coercivity mechanism doesn't require complicated microstructure developments and opens potential for advanced manufacturing. The mechanism is regulated by Cu, and pinning occurs on the extent of 3D defects originating from structural imperfections observed in the as-cast material and develops into Cu-enriched and Co-depleted regions in the thermally aged material. Our recent comprehensive optimization showed that this critical-rare-earth-free and cost efficient gap magnet can reach the energy performance (BH)max. levels of 14 – 15 MGOe, with Curie temperatures of 400 – 500 oC, remanent magnetizations of 7.5 – 8.5 kG and coercivities of 4 – 5 kOe.
9:50 AM
The Mechanical and Magnetic Properties of Mn-Al-C-Cu Alloys: Florian Juerries1; Kornelius Nielsch1; Thomas Woodcock1; 1Leibniz IFW Dresden
The L10 structured τ-phase of the Mn-Al-C system gained interest for the potential use as a rare earth (RE) free hard magnetic material. Warm extrusion is a promising route to optimise the extrinsic magnetic properties of MnAl-C alloys; however, the high stresses involved reduce the lifetime of the extrusion tools, which in turn raises the production costs [1]. It has been reported that Cu addition can reduce the force needed for extrusion without negatively affecting the magnetic properties [1] but the mechanism behind this effect was not shown. In the current work, the effect of Cu additions on the microstructure, mechanical and magnetic properties of MnAl-C alloys in various states has been investigated in detail.<br> <br>[1] S. Kojima, K. Kiyoshi, and S. Mitami, “Permanent Magnetic Mn-Al-C Alloy,” 4133703, 1979.
10:10 AM Break
10:30 AM Invited
Low-dimensional Hard Magnetic Materials: J. Ping Liu1; 1University of Texas at Arlington
We have worked in the past decades on bottom-up approaches to produce nanoparticles, nanorods/nanowires with high magnetic anisotropy including shape anisotropy. The approaches start from synthesis of ferromagnetic nanoparticles with modified solvothermal and other novel synthesis techniques. We have successfully synthesized monodisperse nanorods, nanowires and submicron chips of ferromagnetic FeCo, FePt, CoNi, CoCx and Co based materials. Randomly oriented nanorod/nanowire assemblies show decent room temperature coercivity for their shape anisotropy, while alignment of the rods/wires significantly enhances the magnetic hardening. The aligned Co nanowires have their coercivity values exceeding 12 kOe, comparable to rare-earth permanent magnets. In view of the conventional AlNiCo permanent magnets that have been used for many decades, these types of nanorods/wires may be used as building blocks for advanced bulk and thin film permanent magnets with reduced materials cost and improved thermal stability in the future.
11:00 AM Invited
Synthesis of α″-Fe16N2 Foils for Bulk Rare-earth-free α″-Fe16N2 Permanent Magnet and its Potential Applications: Jian-Ping Wang1; 1University of Minnesota, Twin Cities
α″-Fe16N2 has been proposed and investigated as one of the most promising candidates for rare-earth-free magnets because of its environment-friendly materials. We have addressed several concerns related with its basic performances, including the confirmation of its giant saturation magnetization, large magnetic anisotropy and reasonable decomposition temperature. In this talk, I report a foil-based approach to synthesize bulk α”-Fe16N2 magnet. First, an oxidation and reduction process is applied on iron foils to tune its microstructure, then a nitriding process is carried out. A high volume ratio of α”-Fe16N2 phase is achieved. The obtained saturation magnetization of foils is 10% higher than that of pure iron foils. A coercivity up to 1400 Oe is obtained, which could be further enhanced by reducing the exchange coupling between α”-Fe16N2 grains. An ultra-low temperature coefficient of coercivity of α”-Fe16N2 is confirmed for foils. I will discuss several niche applications for α”-Fe16N2 magnet.
11:30 AM Invited
Visualizing the 2D and 3D Magnetic Domain Evolution Processes in Nd-Fe-B Sintered Magnet by Advanced X-ray Microscopy: Motohiro Suzuki1; Kentaro Toyoki1; Tetsuya Nakamura2; 1JASRI; 2ESICMM
Permanent magnet materials, used for high-efficiency electric motors for low-emission hybrid/electric vehicles, and high-efficient electric power generators, are regarded as vital to the sustainable society. The energy-serving performance of these products is desired to be improved by developing a new permanent magnet material that has superior characteristics, such as higher coercivity and increased maximum energy product. In this study, we used state-of-the-art synchrotron-based X-ray magnetic microscopy techniques to provide new insights of the magnetization reversal process in an Nd-Fe-B sintered magnet, which are closely related to the underlying mechanism that can emerge high coercivity. A scanning two-dimensional X-ray magnetic microscopy under high magnetic field successfully visualized the magnetization reversal processes by grain-by-grain manner, demonstrating the creation of reversed magnetic domains and domain evolutions. Another three-dimensional X-ray magnetic tomography technique allows us to see through the magnetic domains inside a bulk magnet.