Nd-Fe-B die-upset and anisotropic bonded magnets (invited)

Journal Article · Tue Nov 15 04:00:00 EST 1988 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.342394· OSTI ID:7015920

Nozawa, Y; Iwasaki, K; Tanigawa, S; Tokunaga, M; Harada, H

The hot working conditions were examined for Nd-Fe-B die-upset magnets. The Nd/sub 14/Fe/sub 80/B/sub 6/ ternary composition has the best workability (die upsetting) from stress-strain curves for the initial stage of die upsetting at hot working temperature. The compression ratio defined as the inverse of reduction in height should be larger than 4 to have materials aligned. Alignment of c axis along the compressive stress direction is obtained, but grain coarsening occurs during die upsetting. Of several additional elements investigated, Ga is the best for enhancing the coercivity with a little sacrifice of remanence and no deterioration in hot workability. Typical magnetic properties for Nd/sub 14/Fe/sub 79.25/B/sub 6/Ga/sub 0.75/ die-upset magnets are B/sub r/ = 12.4 kG, /sub i/H/sub c/ = 19 kOe, and (BH)/sub max/ = 36 MGOe. The irreversible loss after exposure up to 160 /sup 0/C is under 10% (P/sub c/ = 2). The /sub i/H/sub c/ of powder made by crushing the die-upset magnets is nearly independent of particle size. Decrease in /sub i/H/sub c/ by pulverizing to several hundred micron is about 2 kOe. Anisotropic bonded magnets were developed using this powder. Best energy products of injection and compression molded magnets with Ga addition are 10 and 15 MGOe, respectively. The irreversible losses after exposure up to 120 /sup 0/C is lower than 5% (P/sub c/ = 2), which is enough thermal stability for polymer-bonded magnets.

• Research Organization: Magnetic and Electronic Materials Research Laboratory, Hitachi Metals, Ltd., 5200 Mikajiri Kumagaya, Saitama 360, Japan
• OSTI ID: 7015920
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 64:10; ISSN JAPIA
• Country of Publication: United States
• Language: English

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BORON COMPOUNDS
FABRICATION
INTERMETALLIC COMPOUNDS
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MAGNETIZATION
MAGNETS
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