The current portfolio of advanced permanent magnets heavily relies on rare earth elements that present significant supply chain vulnerabilities and environmental challenges. These issues drive research into alternative permanent magnet systems that could reduce or eliminate rare earth dependence.
Ferromagnetic L10-type compounds, with a high degree of atomic ordering, exhibit substantial magnetocrystalline anisotropy, making them strong candidates for permanent magnet applications. Among these, L10 FeNi (aka. tetrataenite) is particularly promising. Comprised exclusively of easily accessible, low-cost, and non-toxic elements, L10 FeNi exhibits intriguing hard magnetic properties with a high theoretical energy product ((BH)max = 42 MGOe (335 kJ/m3). However, laboratory-scale production of bulk tetrataenite remains unachievable due to the extremely low atomic mobilities (~ 1 atomic jump per 2,600 years) below its ordering temperature of 320 °C, where the atomically disordered fcc phase transforms into the L10-ordered structure. Tetrataenite is found naturally only in meteorites that form over billions of years.
Ongoing research efforts are being directed toward understanding the various factors that influence L10 phase formation and stability, including studies of other L10-forming proxy systems such as MnAl, FePd, FePt, etc. These investigations aim to develop fundamental insights that will ultimately guide the synthesis of tetrataenite on laboratory time scales.
Relevant Publications:
Lewis, L. H., & Stamenov, P. S. (2024). Accelerating Nature: Induced Atomic Order in Equiatomic FeNi. Advanced Science, 11(7), 2302696.
Woodgate, C. D., Lewis, L. H., & Staunton, J. B. (2024). Integrated ab initio modeling of atomic order and magnetic anisotropy for rare-earth-free magnet design: effects of alloying additions in L10 FeNi. arXiv preprint arXiv:2401.02809.
Woodgate, C. D., Patrick, C. E., Lewis, L. H., & Staunton, J. B. (2023). Revisiting Néel 60 years on: The magnetic anisotropy of L10 FeNi (tetrataenite). Journal of Applied Physics, 134(16).
Maât, N., et al. (2020). Creating, probing and confirming tetragonality in bulk FeNi alloys. Acta Materialia, 196, 776-789.
Montes-Arango, A. M., Marshall, L. G., Fortes, A. D., Bordeaux, N. C., Langridge, S., Barmak, K., & Lewis, L. H. (2016). Discovery of process-induced tetragonality in equiatomic ferromagnetic FeNi. Acta Materialia, 116, 263-269.
Bordeaux, N., Montes-Arango, A. M., Liu, J., Barmak, K., & Lewis, L. H. (2016). Thermodynamic and kinetic parameters of the chemical order–disorder transformation in L10 FeNi (tetrataenite). Acta Materialia, 103, 608-615.
Montes-Arango, A. M., Bordeaux, N. C., Liu, J., Barmak, K., & Lewis, L. H. (2015). L10 phase formation in ternary FePdNi alloys. Journal of Alloys and Compounds, 648, 845-852.
Poirier, E., Pinkerton, F. E., Kubic, R., Mishra, R. K., Bordeaux, N., Mubarok, A., … & Barmak, K. (2015). Intrinsic magnetic properties of L10 FeNi obtained from meteorite NWA 6259. Journal of Applied Physics, 117(17).
McCallum, R. W., Lewis, L. H., Skomski, R., Kramer, M. J., & Anderson, I. E. (2014). Practical aspects of modern and future permanent magnets. Annual Review of Materials Research, 44(1), 451-477.
Manchanda, P., Skomski, R., Bordeaux, N., Lewis, L. H., & Kashyap, A. (2014). Transition-metal and metalloid substitutions in L10-ordered FeNi. Journal of Applied Physics, 115(17).
Lewis, L. H., Pinkerton, F. E., Bordeaux, N., Mubarok, A., Poirier, E., Goldstein, J. I., … & Barmak, K. (2014). De magnete et meteorite: cosmically motivated materials. IEEE Magnetics Letters, 5, 1-4.