A Rapid Thermal‐Radiation‐Assisted Sintering Strategy for Nd–Fe–B‐Type Magnets

• Published in: Advanced engineering materials
• Main Authors: Tomše, Tomaž, Ivekovič, Aljaž, Kocjan, Andraž, Šturm, Sašo, Žužek, Kristina
• Format: Journal Article
• Language: English
• Published: 24-09-2024
• ISSN: 1438-1656; 1527-2648
• DOI: 10.1002/adem.202401404

The green transition has spiked demand for high‐performance sintered Nd–Fe–B permanent magnets, necessitating advanced powder consolidation technologies to enhance production efficiency. This study explores the rapid sintering methodology for an Nd–Fe–B powder using a radiation‐assisted sintering approach. The case study material is an industrially used powder, prepared through strip‐casting, hydrogen decrepitation, and jet milling, with a mean particle size of 5.5 μm. The powder is sintered to full density in a modified spark plasma sintering furnace, achieving pressureless conditions and eliminating electrical currents in the sample to preserve grain alignment and prevent decomposition of the hard‐magnetic phase. Fully dense samples are obtained with heating rates ranging from 10 to 200 °C min −1 and up to 5 min of dwell time at 1100 °C. Rapid heating results in grain size and microstructure comparable to conventionally sintered magnets prepared from the same powder, without compromising magnetic performance after postsinter annealing at 520 °C for 120 min. This sintering method contributes to a novel strategy for optimizing magnet production by utilizing efficient thermal‐radiation heat transfer. The combination of rapid heating and pressureless sintering drastically reduces heat‐up and dwell times, providing a fundamental advantage over slow conventional sintering.