Lower cost and more stable supplies of strong neodymium magnets, used in motors and generators, could be a reality as soon as 2017, as Japanese researchers use a powerful magnetic-reversal simulator to find a way to eliminate dysprosium from the equation.
The increasing requirements from the automotive, energy conservation and generation sectors have increased demand for neodymium magnets. There is also a focus on improving the efficiency of motors and generators that use magnetic materials.
In conventional high-performance neodymium permanent magnets, dysprosium alloying is essential for enhancing magnetic coercivity, which allows the magnet to withstand an external magnetic field without becoming demagnetised, especially when used in motors and generators.
However, as a natural resource, dysprosium is only about 10% as common as that of neodymium. Additionally, geopolitical conditions around the world contribute to growing fears about the stability of supply for this rare earth element.
Fujitsu, along with the National Institute for Materials Science and Fujitsu Laboratories, developed the world's largest magnetic-reversal simulator, using a mesh covering more than 300 million micro-regions, in order to examine the mechanism of coercivity in neodymium magnets, and how the fine structure of the material reacts when subject to a demagnetisation field.
Magnetic-reversal simulation technology was first developed in 2013, but the newest development uses a faster calculation algorithm and more efficient massive parallel processing, with the simulations running on Fujitsu's K supercomputer.
With the new computing capabilities, the researchers conducted large-scale simulations using a highly detailed mesh with more than 300 million nodes. This number-crunching revealed a way to develop high-strength neodymium magnets with more than twice the coercivity of previous magnets, without having to rely on dysprosium.
The research team created a polycrystalline model in which 27 neodymium-magnet crystals were magnetically bonded, and simulated the process of magnetic reversal while varying the strength of the magnetic couplings between the crystals.
They found that they could greatly increase the resistance to demagnetisation by magnetically decoupling the crystal grains in the lateral direction. On the other hand, decoupling the grains in the perpendicular direction did not have much effect.
This means it is possible to modify the structure of neodymium magnets in order to increase their magnetic coercivity, without having to use dysprosium.
With a clear direction on how to proceed, the researchers say they will continue the research by using targeted simulations, with the goal being to develop dysprosium-less neodymium magnets by 2017.