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Die - upset법에 의한 Pr - Fe - B자석의 자기적 성질에 관한 연구
이경섭(K. S. Lee),서수정(S. J. Suh),박현순(H. S. Park),이병규(B. G. Lee),정지연(J. Y. Jung) 한국자기학회 1993 韓國磁氣學會誌 Vol.3 No.3
Starting ingot of Pr_(15)Fe_(77)B_8 were prepared by vacuum induction melting under argon atmosphere. The ingot were induction melted in a quartz crucible and then ejected as a molten alloy throuth a 0.6 ㎜ orifice onto a rotating copper wheel. An anisotropic magnet was prepared from ribbon by hot deformation techniques. A fully dense precursor magnet first made by pressing ribbons at 680 ℃ under a pressure of 21.8 ㎏ / ㎟. A substantially oriented magnets were obtained by die-upset under various conditions. As the compression ratio increases, the Br value increases pronouncedly though iHc decreases. Also, XRD analyses show increased diffraction peak from (006). From these results, it can be known that the magnetic easy axis was formed along the compression axis. As the die-upset speed increases, iHc increases though Br decreases. The Br increases up to 750 ℃ of die-upset temperature and above this temperature decreases. The value of 4πMs of the Pr_(15)Fe_(77)B_8 alloy prepared is found to be 11.8 KG. When the alloy was compressed by 0.8 under the die-upset speed of 0.05 m/sec at 750 ℃r B, was 11.0 KG indicating that the alloy has excellent magnetic anistropy. However, this alloy has some limitation because of low iHc.
Hot Press 및 Die - Upset 법에 의해 제조된 Nd - Fe - B - Co 자석의 자기적 특성
이경섭(K. S. Lee),김용성(Y. S. Kim),서수정(S. J. Suh),박현순(H. S. Park),박찬(C. Park) 한국자기학회 1997 韓國磁氣學會誌 Vol.7 No.1
The effect of Co and annealing temperature on the magnetic properties, phase change and microstructure of melt-spun (Nd_(14.73)Fe_(78.67)B_(6.60))_(100-x)Co_x (X=0, 1, 2, 3) ribbons has been studied. The Co containing ribbons were found to have higher coercivity (iHc) than the ribbons without Co. Intrinsic coercivity of 20.3 kOe has been obtained by addition of 2 at%Co. This effect by Co addition is also represented in the case of hot pressed and die-upseted magnets. The maximum intrinsic coercivities of hot press and die-upset (Nd_(14.73)Fe_(78.67)B_(6.60))_(100-x)Co_x (X=0, 1, 2, 3) magnets are 16.9 kOe and 15.2 kOe when X=2.