Processing of high-performance anisotropic permanent magnets by die-upset forging

Effects of Nd-rich phase on the improved properties and recoil loops for hot deformed Nd-Fe-B magnets

“…Furthermore, it has been suggested that a high deformation ratio also induce the non-uniform distribution of the Nd-rich phase in HD magnets [21]. In this work, we employed a high density SPS precursor and a high deformation temperature of 800 C to increase the deformation ratio to 80%.…”

“…The open loops, again, can be explained based on Nd-rich phase aggregation. For the HD magnets with high deformation ratio, the Nd-rich phase can be squeezed out from grain boundaries due to serious deformation [21], which causes a slightly non-uniform distribution of the Ndrich phase. The resulting recoil loops, therefore, are slightly open.…”

Effect of hot deformation on texture and magnetic properties of Sm–Co and Pr–Co alloys

“…In hot-deformed Nd-Fe-B alloys, the texture formation is believed to be dominated by preferential growth of the R 2 Fe 14 B grains having the [0 0 1] axis oriented parallel to the press direction [8,[10][11][12][13][14][15]. The reason why grains with this orientation are growing under pressure at the expense of the other grains is the well documented tendency of the Nd 2 Fe 14 B crystals to grow perpendicularly to the [0 0 1] axis [10,16,17].…”

“…The reason why grains with this orientation are growing under pressure at the expense of the other grains is the well documented tendency of the Nd 2 Fe 14 B crystals to grow perpendicularly to the [0 0 1] axis [10,16,17]. Since for RCo 5 single crystals such tendency has not been reported [18,19], the other possible mechanisms of the texture development considered for the Nd-Fe-B alloys (plastic deformation of the grains [20,21] and grain-boundary sliding [13,15,21]), cannot be ruled out in the case of the RCo 5 alloys. It should be noted, however, that the grain growth during the hot deformation of the RCo 5 alloys at 950 1C was considerable (judging from our earlier experiments with annealed and hot-pressed HEBM SmCo 5 alloys [22,23] the average grain size of the precursors compacted at 650 1C must have been in the range of a few tens of nanometers).…”

Origins of Radial and Axial Inhomogeneity of Magnetic Performance in Cylindrical Nd-Fe-B Magnet Prepared by Hot Deformation

“…H OT DEFORMED (HD) Nd-Fe-B magnets exhibit good magnetic performance [1], [2], corrosion resistance [3], [4] and thermal stability [5]. Therefore, increased attention has been drawn to them in both basic and application research fields [6]- [8], focusing mainly on ring-shaped and cylindrical HD magnets [9].…”