In recent decades rare-earth-element Nd-Fe-B permanent magnets have significantly shaped the global technological landscape. These magnets can be found in crucial technologies such as motors, generators, electric cars, wind turbines and an expansive range of consumer electronics [1,2]. The European magnet industry faces a myriad of challenges that must be overcome to maintain its international competitiveness amidst the heavily subsidised Chinese market. The primary challenge is to achieve a more efficient use of critical materials, a priority underscored by the European Commission (EC) in the Critical Raw Materials Act 20233. The emphasis is on heavy-rare-earth elements, recognising their pivotal economic significance and susceptibility to supply risk [3,4].

The study sought to tune the microstructures of sintered Nd-Fe-B PMs to create more resource-efficient magnets. A novel rapid sintering technique was adopted, aiming for improved magnetic properties beyond those achievable with conventional methods. The primary focus was on boosting the coercivity while minimising the use of Dy. A powder blending approach was taken to improve the performance of magnets based on a 1 wt.% Dy-containing Nd-Fe-B feedstock with small additions of NdH₃ and nanosized DyF₃ powders. Various powder mixtures were examined, including the addition of 3 wt.% NdH₃, 0.5 wt.% DyF₃, 1.0 wt.% DyF₃, and a combination of 1 wt.% NdH₃ and 1 wt.% DyF₃. A range of sintering procedures and annealing parameters were applied. A comprehensive investigation of the effects of the sintering and annealing conditions on the microstructure formation and magnetic characteristics of the material was performed. The study was performed in the frame of EIT RAW Materials project RECO2MAG.

[1] Gauß, R. et al. Rare Earth Magnet and Motors: A European Call for Action. (2021).

[2] Walton, A., Anderson, P., McGuiness, P. & Ogrin, R. Securing Technology-Critical Metals for Britain - Ensuring the United Kingdom’s Supply of Strategic Elements & Critical Materials for a Clean Future. (University of Birmingham, 2021).

[3] European Union. Critical Raw Materials Act. https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials/critical-raw-materials-act_en (2023).

[4] Goodenough, K. M., Wall, F. & Merriman, D. The Rare Earth Elements: Demand, Global Resources, and Challenges for Resourcing Future Generations. Natural Resources Research 27, 201–216 (2018).