MP Materials USAR Lawsuit Raises Stakes in US Rare Earth Magnet Race

MP Materials USAR

MP Materials USAR lawsuit has opened a new front in the race to build domestic rare earth magnet capacity, with MP accusing rival USA Rare Earth of misappropriating proprietary magnet technology through a former employee. The dispute centres on grain boundary diffusion technology, a key process used to improve high-performance neodymium-iron-boron magnets.

MP Materials USAR lawsuit was filed in Texas Business Court on 26 May. MP is seeking injunctions against all USAR entities and alleges that a former employee improperly disclosed sensitive formulas and processes to the rival company.

MP Materials USAR lawsuit is strategically important because both companies are building large US magnet production platforms. The dispute could affect investor confidence, customer qualification and the timing of domestic magnet supply for defence, automotive and industrial users.

The case also shows that the US rare earth sector has moved beyond mining and separation. Competition is now intensifying around process know-how, metallization, alloying, powder metallurgy and magnet finishing.

Grain Boundary Diffusion Becomes a Competitive Battleground

Grain boundary diffusion is an important technology in high-performance NdFeB magnet production. It can improve magnet performance and reduce the use of costly heavy rare earths in certain applications.

That makes the process commercially valuable. Rare earth magnets used in defence, electric motors, robotics and aerospace systems must meet strict performance, heat resistance and reliability requirements.

MP alleges that its proprietary grain boundary diffusion technology was developed through years of work and significant investment. The company claims former employee Kevin Elkins had access to extremely sensitive formulas and processes before joining USAR.

MP also alleges that USAR recruited several MP employees since 2025, including Elkins and at least seven other key staff. MP described this as part of a broader trade secret raiding campaign.

These remain allegations, and the court process will determine the outcome. But the filing highlights a real industrial issue: skilled people and protected know-how are now as important as rare earth feedstock in the US magnet supply chain.

Legal Dispute Adds Risk to Domestic Magnet Scale-Up

Both companies are trying to scale US magnet production quickly. MP is expanding its Independence facility in Fort Worth, Texas, to 3,000 t/yr, including metallization, alloying, powder metallurgy, grain boundary diffusion and magnet finishing.

MP is also building a larger Texas facility to raise total magnet production to 10,000 t/yr. That expansion is central to its ambition to create a fully integrated rare earth-to-magnet supply chain in the US.

USAR also plans to produce 10,000 t/yr of magnets by 2029, up from current capacity of 4,800 t/yr. The overlap between these expansion targets makes the legal dispute commercially sensitive.

For the US government and downstream customers, the case creates a difficult dynamic. Washington needs multiple domestic magnet suppliers, but those suppliers also need enforceable intellectual property protections.

The dispute could slow collaboration, complicate customer qualification or increase caution around hiring and technology transfer. It may also push rare earth companies to tighten controls over employee access, process documentation and proprietary manufacturing routes.

The broader message is clear. Domestic magnet capacity will not be secured only through capital spending. It will require protected process technology, skilled labour, validated production and trusted commercial behaviour.

The Metalnomist Commentary

The MP-USAR dispute shows that the rare earth magnet race is becoming a technology and intellectual property contest. The US needs faster magnet scale-up, but it also needs clear rules that protect proprietary process know-how while keeping domestic supply-chain development on track.