EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

REFeB permanent magnets have drawn attention due to their excellent magnetic properties and wide applications, such as in magnetic resonance imaging, electric vehicle, wind generator, factory automation system etc. Usually magnets are made by sintering pulverized powder obtained through strip casting or melt spinning process, but these traditional methods are complex and powders can be easily oxidized due to their increased surface area. In order to overcome this problem, several studies have investigated hot plastic deformation using gas atomized powder.
Meanwhile, as known that the magnetic properties of PrFeB magnet can be enhanced by plastic deformation from casting ingot due to alignment to easy magnetization axis and grain refinement of hard magnetic phase. But the ingot has large grain and high fraction of α-Fe phase due to slow cooling rate. Meanwhile, gas atomization process is well known process on the making metal powder and its cooling rate is faster than casting ingot so it can make fine microstructure, so if we make the PrFeB magnet using gas atomization and plastic deformation, the magnetic properties are getting more higher than casting ingot due to not only getting more fine microstructure but also getting more hard magnetic phase owing to rapid cooling rate.
In this study, we tried plastic deformation of PrFeB alloy fabricated by gas atomization process. The PrFeB powder was made by gas atomization process in vacuum condition, and the powder was sieved. And each powder was pre-compacted by spark plasma sintering. The PrFeB billets were plastic deformed at 600, 700 and 800℃ at variable reduction ratio. The magnetic properties of PrFeB billets were measured by B-H tracer, grain size and microstructure were observed by scanning electron microscopy and X-ray diffraction. Finally, we obtained a result that gas atomized powder can be used to PrFeB magnet.