Couple of days ago, i got a question for hot topic referring to what are the best relatively possible ways to reduce dysprosium (Dy) percentages from Neodymium magnets (Nd2Fe14B), actually for this question there were researches and practices for a long time and seems will last further and further as it is a moving target. From Quora I see an engineer who replied this question very professionally so i'd like to recommend it for your consideration.
There are a number of different methods to reduce Dy use in rare earth magnets:
- Reduce grain size. Dy is added to increase coercivity (it’s naturally higher in that quality than Nd). But NdFeB depends on the domains at the grain wall for its coercivity (known as “pinning”) so if you just reduce the grain size the alloy will naturally increase in coercivity. But “just” reducing the grain size while keeping the other qualities that make the alloy useful is a highly non-trivial challenge. This method will save Dy but not necessarily cost.
- Grain boundary diffusion. Rather than adding Dy to the melt at the beginning of the manufacturing process, you can add it at the end by exposing the finished magnet to Dy in a bath or atmosphere. This works but the size and shape of the magnet are limited and it’s an extra step that so far can produce variable results.
- Terbium. Use Tb instead of Dy. Tb has even higher coercivity than Dy. But it’s even more expensive.
- Redesign the magnet to have a higher permeance coefficient. Then it won’t need as high a coercivity. This can save both cost and Dy, but it’s not always possible.
These are just examples from current technology. There are other methods. Dy reduction is an active area of research and thus a moving target.
From https://www.quora.com/What-is-the-best-possible-way-to-reduce-Dysprosium-Dy-percentage-from-the-Neodymium-Nd2Fe14B-magnets
From https://www.quora.com/What-is-the-best-possible-way-to-reduce-Dysprosium-Dy-percentage-from-the-Neodymium-Nd2Fe14B-magnets
