Materials Engineering of Soft Magnets for Power and Energy Applications: Advanced Soft Magnetic Material Characterization and Development Techniques
Sponsored by: TMS Functional Materials Division, TMS: Energy Conversion and Storage Committee, TMS: Magnetic Materials Committee
Program Organizers: Paul Ohodnicki, National Energy Technology Laboratory; Francis Johnson, GE Global Research; Alex Leary, Carnegie Mellon University; Tanjore Jayaraman, University of Michigan; Lajos Varga, Wigner Research Center for Physics

Thursday 8:30 AM
March 2, 2017
Room: 25B
Location: San Diego Convention Ctr

Session Chair: Lajos Varga, Wigner Research Centre for Physics; Tanjore Jayaraman, University of Michigan

8:30 AM  Invited
Advanced Magneto-Optical Domain Analysis in Soft Magnetic Materials: Rudolf Schaefer1; 1Leibniz Institute for Solid State and Materials Research (IFW) Dresden
    A review will be given on the possibilities and recent developments of magnetic domain imaging by wide-field magneto-optical Kerr microscopy with emphasize on soft magnetic materials. This includes vectorial imaging, quantitative Kerr microscopy of complete magnetization processes, high-resolution domain wall studies, and time-resolved domain imaging in single-shot and stroboscopic modes. Typical examples of favorable and unfavorable domain processes in terms of energy loss will be presented on a variety of materials including electrical steel, amorphous and nanocrystalline ribbons, and magnetic films. Also the role of microstructure for domain formation and flux propagation will be addressed.

9:00 AM  
Multi-parameter Magnetic Material Characterization for High Power Medium Frequency Converters: Richard Beddingfield1; Subhashish Bhattacharya1; 1North Carolina State University
    With the rapid availability of new magnetic materials and even more options in post-processing techniques such as field and strain annealing, full property maps of materials and final fabricated components are needed for proper system design. This is especially critical in modern wide-bandgap power electronics based converters where medium switching frequencies are used to deliver high power. In these systems, the magnetic design has a significant impact in the overall losses. The magnetics constitute a majority of the losses and magnetic properties have a defining influence on the overall systems, e.g. available power flow and soft switching regions. A new lossless structural harness that allows easy testing of cores and the development of property maps is presented. The harness also enables the testing of mechanical variations such as gapping and clamping pressure on the core.

9:20 AM  Invited
Unique Magnetostriction of Fe68.8Pd31.2 Attributable to De-twinning Mechanism: Jake Steiner1; Abdellah Lisfi2; Tomoyoki Kakeshita3; Takashi Fukuda3; Manfred Wuttig1; 1University of Maryland; 2Morgan State University; 3Osaka University
    Fe68.8Pd31.2 exhibits an anomalously large magnetostriction of 400 ppm at room temperature as well as linear, isotropic, and hysteresis free magnetization behavior. This near perfectly reversible magnetic response is attributable to the presence of a large number of premartensitic twins present in the system made possible through the elastic softening that occurs near a martensitic transformation temperature of 250 K. It is proposed that the twins in the material reduce both elastic and magnetic self energy, causing the elastic and magnetic behavior of the material to be intimately linked. In such a framework, the anisotropy energy becomes extremely low causing the material to bear no crystalline dependence on magnetization, and application of a magnetic field causes simultaneous magnetic and twin domain movement, which, upon removal of the field, relaxes the system.

9:50 AM Break

10:05 AM  
Large Magnetocaloric Effect in Ga Substituted NiMnIn Metamagnetic Shape Memory Alloys: Jasone Estalayo1; Christian Aguilar2; Daniel Salazar3; Pablo Alvarez-Alonso1; Patricia Lazpita1; Juan Camarillo2; Horacio Flores-Z˙˝iga2; Volodymyr Chernenko3; 1Dept. Electricity & Electronics, University of the Basque Country; 2IPICYT; 3BCMaterials
    Metamagnetic shape memory alloys (MMSMAs) represent a new kind of multifunctional materials that show inverse magnetocaloric effect as a consequence of a magneto-structural transformation (martensitic transformation MT). In this work we report on the effect in the MT and magnetocaloric properties of Ga substitution for Ni in Ni50Mn34In16 alloys. Ga substitution induces an increase in the MT from 250 K to 305 K and a reduction of Curie point in the austenite phase. We have analysed the magnetocaloric response associated to the MT and the magnetic phase transition in the austenite phase by estimating the magnetic entropy change and measuring directly the adiabatic temperature change, ΔTad. The alloys present inverse MCE with large values of ∆Tad (until 2.7K at ∆H=1.9 kOe) associated with the paramagnetic martensite to ferromagnetic austenite phase transition. Conventional MCE (∆Tad=1.2 K under ∆H=9 and 1.9kOe respectively) occurs at the magnetic phase transition in the austenite phase.

10:25 AM  
Direct Measurement of the Magnetocaloric Effect in NiMnIn Ribbons: Christian Aguilar1; Pablo Alvarez-Alonso2; Daniel Salazar3; Horacio Flores-Z˙˝iga1; Volodymyr Chernenko3; 1IPICYT; 2Dept. Electricity & Electronics, University of the Basque Country; 3BCMaterials
    Magnetic shape memory alloys (MSMAs) are unique materials thanks to large changes in their magnetic properties induced by the martensitic transformation. These changes are at the origin of high magnetocaloric responses, whereby these alloys have attracted much attention due their potential use in magnetic refrigeration. We studied Ni50Mn35In15 alloys melt-spun at different wheel speeds (10, 20, 30, 40, and 50 m/s) to analyse the impact of the cooling rate on the structure, magnetic and magnetocaloric properties. We have studied the magnetocaloric effect (MCE) associated to both the MT and the magnetic phase transition in the austenite phase by estimating the magnetic entropy change ΔSM from magnetization measurements, and measuring directly the field-induced adiabatic temperature change, ΔTad. Ribbons present a conventional MCE (ΔTad~2.2 K at ΔH=19 kOe for v=10 m/s) as a consequence of the ferro-to-paramagnetic transition in the austenite phase, and inverse ΔTad ~-1.1 K under ΔH=19 kOe at MT.

10:45 AM  
Combinatorial High-throughput Discovery of Magnetic Materials in Thin Films: Abraham Anapolsky1; 1Intermolecular Inc.
    At Intermolecular, we are developing high-throughput techniques to synthesize and characterize materials based on multinary (high entropy) alloys. We use a two-fold approach, using DFT methods to predict single-phase stability, and PVD to synthesize composition spreads in thin (~300nm) films. Magnetic materials are of interest, because intrinsic magnetic properties of a material are similar in thin film as bulk. We have explored a bulk system published by Zhang, Zuo, and Liaw (2015), [CoFeNi]_x-[AlSi]_y (pseudo-binary). In our work we extended this system to a pseudo-ternary, [CoFeNi]x-Al_y-Si_z. Composition, phase, and magnetic properties agreed with published bulk values. Our methodologies were optimized for high-throughput, thus with the generation of three samples we were able to populate the portion of the ternary [CoFeNi]-Al-Si that is bounded by magnetic properties. Intermolecular will also be exploring optimization of magnetocaloric materials using high throughput combinatorial methods, this work will also develop in-situ techniques to characterize magnetocaloric properties.