Rare-Earth-Free Iron-Nickel-based ordered phases for permanent magnet applications

Permanent magnets (PMs) are crucial components in many modern technologies and have gained a prominent role in energy applications, as they allow the conversion of mechanical work into electricity and vice versa. Currently, the best performing PMs are based on rare-earth (RE) containing phases. But the commercial production of RE-PMs suffers a few serious drawbacks. Since the early 2000s, the source of rare-earths has been geographically concentrated in China, which has imposed strict export quotas and taxes. This has caused a steep increase of the price of RE and severely affected the supply chain of PM raw materials, the so-called rare-earth crisis. Due to the limited availability and high volatility in price, REs are considered by the EU critical raw materials and there has been an increasing need to develop high performance magnets with no (or very limited) rare-earth elements. Tetrataenite, an ordered intermetallic ferromagnetic compound composed of readily available Fe and Ni, has recently been considered the most promising material for substituting REs in permanent magnet applications. In nature, tetrataenite has been found only in meteorites and its synthesis is extremely challenging. REFINE’s ambition is to accomplish a clear progress beyond the state-of-the-art within the laboratory production of ordered Fe-Ni-based phases. Mechanical activation processes, such as mechanical alloying, cryomilling and cold rolling, are used to enhance short-range atomic rearrangements and provide a drive towards chemical ordering and improved magnetic performances. Ultimately, REFINE's objective is to develop and produce a next-generation high-performing rare-earth-free magnetic material for permanent magnet applications, containing low-cost, abundant, non-critical raw elements. The core activities are part of the work plan for a PhD student, who has started working in December 2021. The main experimental tasks performed in 2023 are a continuation of the efforts initiated the previous year. Mechanical processing of pre-alloys produced by ball milling and arc melting was performed either by cryomilling or by cold rolling. Melt spinning performed by our R&D partner IPSAS (Slovakia) was also used to produce different batches of starting materials containing small elemental additions. After mechanical processing, all samples were subjected to long-term annealing at low temperatures to promote the formation of the tetrataenite phase. To investigate the effect of structural defects and small elemental additions on the ordering process, synchrotron powder X-ray diffraction was performed at the Swiss Norwegian Beamline at the ESRF in Grenoble and transmission electron microscopy studies are being carried out at the Oslo node of The Norwegian Centre for Transmission Electron Microscopy (NORTEM). The magnetic characterization of the samples is being performed at the University of Oslo.

REFINE's goal is to develop and produce a next-generation high-performing rare-earth-free magnetic material for permanent magnet applications, containing low-cost abundant elements and no critical raw elements. It will address the synthesis of the ordered L10 FeNi phase (tetrataenite), which in nature is found only in some meteorites, by systematically exploring the use of mechanical activation processing and by employing established structural, microstructural and magnetic characterization protocols to outline structure-property relationship in materials tetrataenite-containing materials. REFINE addresses the needs for providing new permanent magnets for smaller, lighter and more energy efficient electric devices, and accelerating the transition from fossil fuels to renewable energy sources and adoption of zero-emission transport modes. In addition to the low-cost of the constituent elements, processing and manufacturing conditions considered in this proposal fulfill the requirements of scalability, eco-efficiency and cost-effective implementation.