Advanced Grain Boundary Diffusion9 Nov 2025 19:30
I have been looking again at Hypromag USA news release fro 09/15/2025. For me the introduction of Advanced Grain Boundary Diffusion techniques into the HPMS magnet production process is very interesting
This is a summary of how it works
Coating: A source of heavy rare-earth elements (like Dysprosium or Terbium), often in the form of a fluoride, hydride, or alloy, is applied to the surface of the magnet.
Heat treatment: The coated magnet is heated to a moderate temperature for several hours.
Diffusion: The heavy rare-earth elements move from the surface into the magnet, predominantly following the grain boundaries (the interfaces between magnetic grains).
Result: This forms a thin, protective layer of heavy rare-earth elements around the magnetic grains, which improves coercivity without significantly reducing the magnet's remanence (overall magnetic strength).
Advantages of advanced GBD
HRE conservation: It drastically reduces the amount of expensive and scarce heavy rare-earth elements needed for a high-performance magnet, sometimes by an order of magnitude, by placing them where they are most effective.
Increased coercivity: The process significantly boosts the magnet's resistance to demagnetization.
Maintained remanence: Unlike conventional alloying, it avoids diluting the main magnetic phase, helping to maintain the overall magnetic strength (remanence).
Customization: It allows for the creation of magnets with higher grades and specific properties (e.g., high coercivity) that were not possible with traditional methods.
What this in essence tells me is that Hypromag are working on producing the top tier of high performance magnets used in Defense applications. but with only low content of the expensive heavy rare earths with the majority of cost coming from the comparatively low cost HPMS recycling. This for sure is not just limited to the US but all of Hypromag operations. I can further see that Heavy Rare Earths coming from Malawi mine and separated out in Poland will be supplied to Hypromag facilities. There may be a split between mining/processing and recycling but economically I fully expect long supply arrangements between MKAR and Hypromag. This is something the US DoD will be extremely interested in, we can be sure.
Also need to be understood that the details around these matters and cooperation with US/EU defense industry is highly confidential.