Advanced Magnetic Materials for Energy and Power Conversion Applications: Magnetocalorics and Energy Harvesting
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

Tuesday 2:00 PM
February 25, 2020
Room: Del Mar
Location: Marriott Marquis Hotel

Session Chair: Daniel Salazar, BCMaterials; Senentxu Lanceros-Mendez, BCMaterials


2:00 PM  Invited
Magnetic Shape Memory: Magnetomechanics – MSM Design – Microfluidics – Markets: Peter Mullner1; 1Boise State University
    You may have seen something like magnetic shape memory (MSM) alloys at the movies. In Terminator 2, a “liquid metal” robot faces off against a more traditionally engineered robot. Although not humanoid, MSM alloy uses the same basic principle: it shape-shifts. Apply a magnetic field, and the material responds with a shape change. Apply a different magnetic field and the material re-forms into a new shape. Do this quickly and with purpose and you have a device. Invert the concept and you have a power generator or sensor. MSM alloys present a paradigm for actuation and sensing devices. Products can be smaller, lighter and quieter since they have no moving parts to wear out. This presentation introduces (i) the scientific principles including magnetic anisotropy, deformation mechanisms, and magneto-mechanics, (ii) design principles for MSM devices, (iii) MSM technology at the example of a micropump, and (iv) a path to the market.

2:30 PM  Invited
Recent Developments in NiMn-based Martensitic Materials for Actuation and Energy: Volodymyr Chernenko1; 1BCMaterials & University of the Basque Country (UPV/EHU)
     Multifunctional Heusler-type magnetic shape memory alloys (SMAs) can be divided into two groups: ferromagnetic (FSMAs) and metamagnetic (MetaMSMAs). FSMAs are represented by NiMnGa. They exhibit giant magnetic field induced strain in martensitic phase due to mechanism of twin boundary motion. The MetaMSMAs, typically NiMnX (X=Sn, In,Sb), exhibit giant inverse magnetocaloric effect (MCE) in the temperature range of martensitic phase transformation (MT), contrary to NiMnGa alloys with merged MT and Curie temperature that show a giant conventional MCE. Three aspects from recent advances in aforementioned materials will be outlined. 1. Significant progress in the developments of high temperature FSMAs based on multicomponent NiMnGa(Co,Cu,Fe) alloys will be overviewed and discussed. 2. The mechanism of the large magnetostrain self-recovery in NiMnGa/silicone composites exhibiting magnetic field induced rubber-like effect will be disclosed.3. It will be shown how to describe giant inverse MCE in MetaMSMAs and conventional MCE in FSMAs by Landau theory.

2:55 PM  
Engineering Built-in strain Gradients to Tune Magnetism in Two-phase Heusler Intermetallics: Yolita Eggeler1; Emily Levin1; Fulin Wang1; Ram Seshadri1; Tresa Pollock1; Daniel Gianola1; 1University of California, Santa Barbara
    It has recently been proposed that magnetic properties may be influenced by built-in strain gradients arising from the two-phase microstructure in phase separated Heusler intermetallics. The different lattice parameter of the matrix phase and the precipitate phase results in a lattice misfit at the precipitate/matrix interface, which introduce strain gradients in the compound and locally disrupt the crystal symmetry. We hypothesize that built-in strain gradients in two-phase Heusler systems can be engineered to directly mediate magnetic bulk properties and result in emergent magnetic spin texture formations. This work characterizes semi-coherent interfaces in the Nb-Co-Sn two-phase Heusler system. Our results show that the rather large lattice misfit of 3.3% causes a regular array of dislocation pairs, which line up along the precipitate/matrix interface with nanometer separation. Different thermal processing routes are applied to elucidate how this interface structure can be tailored to influence functional properties mediated by magnetic structure.

3:15 PM  Invited
Magnetically Active Composites for All-printed Electronics Applications: Ana Catarina Lima1; Nikola Perinka2; Nelson Pereira1; Vitor Correia1; Pedro Martins1; Senentxu Lanceros Mendez2; 1University of Minho; 2BCMaterials
     Printable materials allows the development of low cost smart devices with low power consumption, easy integration into a variety of surfaces and the possibility to be applied over flexible and large areas. In particular, magnetoelectric (ME) polymer-based smart devices can support the on-going industry 4.0 paradigm as well as the development of sustainable, wireless and interconnected autonomous smart devices, systems and cities (IoT). This work reports on magnetically active and responsive fully printed devices obtained from polymer nanocomposites for sensing, actuation, energy generation and conversion. Materials based on piezoelectric polymers and their nancomposites with different ferrites will be presented and discussed. Further, a new generation of fully screen printed planar transformer and planar and flexible RF power transmission systems will be presented, based on the printing of concentric coils on various formats. The implications of the obtained materials and devices in the area of wearable sensors will be highlighted.

3:45 PM Break

4:05 PM  Invited
Generating Electricity from Waste Heat using Magneto-structural Materials: Ekkes Brueck1; 1Delft University of Technology
     Magneto-caloric power conversion can be used to convert heat into electricity that up to now was considered as waste. With the advent of giant magneto-caloric effects that occur in conjunction with magneto-elastic or magneto-structural phase transition of first order, room temperature heat-pump applications became feasible. In this context the MnFe(P,Si) system is of particular interest as it contains earth abundant ingredients that are not toxic. Other promising materials are based on La(Fe,Si)13. Magneto-caloric power-conversion calls for a somewhat different combination of properties, in particular a large latent heat that is favourable for a heatpump, is detrimental for power conversion as a lot of heat is needed to change the temperature. Yet a large change of magnetization is required to generate a high torque in a device, which suggests one should either employ materials exhibiting exchange inversion or second order materials.

4:30 PM  
Industrial Development of La-Fe-Si Magnetocaloric Alloys for Energy Conversion: Alexander Barcza1; Christian Polak1; 1Vacuumschmelze GmbH & Co. KG
    The commercial success of magnetic refrigeration depends critically on the shaping of magnetocaloric alloys into heat exchange structures having low pressure drop and large surface area. Due to its large magnetocaloric effect, abundant and inexpensive raw materials La-Fe-Si is one of the most promising candidate materials. Its brittleness makes it unsuitable for production processes used for conventional metallic heat exchange structures. We have developed an industrially viable, near net-shaping, powder-metallurgy route for the production of La-Fe-Si microchannel heat exchangers. The structures allow for 2D-connected fluid channels with hydraulic diameters of the order of several hundred micrometers – similar to conventional corrugated fin heat exchangers. The manufacturing techniques used offer large degrees of freedom for the designers paving the way for further commercialization of solid state energy conversion based on the magnetocaloric effect.

5:00 PM  Invited
Magnetic Domains in Magnetostrictive Fe-Ga Alloys: Yongmei Jin1; Matthew Tianen1; 1Michigan Technological University
    Fe-Ga alloys (Galfenol) have attracted great attention as new giant magnetostrictive materials for over fifteen years, however little is known about the domain phenomena underlying their properties. Using Bitter method and domain theory, we investigate the magnetic domain structures in Fe-Ga single crystals. Our domain observation experiments reveal numerous previously unknown domain patterns and their responses to magnetic fields. As a cubic system of high magnetostriction and weak magnetocrystalline anisotropy, the domains on Fe-Ga surfaces are largely determined by the image forces (both magnetostatic and elastostatic) associated with the surfaces, making it challenging to infer inner bulk domains from surface observations, while the bulk domains dominate the material responses. Using domain theory, we analyze the energetics of domain structures near the surfaces to determine the bulk domain structures and their evolutions. The findings advance our understanding of the domain phenomena and mechanisms responsible for the magnetoelastic behaviors of Fe-Ga alloys.