Fabrication, Processing Technologies, and New Advances for RE-Fe-B Magnets

摘要

Over the last 30 years, rare-earth permanent magnets have become an integral part of our lives, driving computers, home appliances, and automobiles. They are set to become an even more prominent component of our future with the growth in clean technologies, such as electric vehicles and wind power generation. This market growth was briefly challenged in 2011 by the threat of supply restrictions and inflated prices from the world’s principle source of rare earths. However, a rational calm has now returned to the market and magnet users can continue to benefit from the high efficiency and miniaturization these phenomenal magnets provide to electromechanical devices. The rare-earth magnet industry and research community continues to innovate and push these magnetic materials toward their theoretical potential, specifically in the areas of higher magnetic performance, lower costs, and greater thermal stability. These development areas for the two principle types of rare-earth iron boride (RE-Fe-B) magnet, sintered and rapidly quenched, are subtly different. The coarser microstructure of sintered magnets has made them more reliant on the less abundant heavy rare-earth elements for magnetic performance at elevated temperatures, so development activity on sintered RE-Fe-B magnets has focused on minimizing this Dy and Tb dependence. Magnets from rapidly quenched RE-Fe-B materials have fine nanostructures, and developments have targeted higher remanence, lower material costs, and protection of the material from oxidizing environments.