The effects of particle size and distribution on the magnetic properties of coercive Sm(Co,Fe,Cu,Zr){ital {sub z}} alloy powders for bonded magnet applications
- Rhone-Poulenc, Rare Earths and Gallium, CN 7500, Cranbury, New Jersey 08512 (United States)
The microstructure of Sm(Co{sub bal}Fe{ital {sub x}}Cu{sub 0.08}Zr{sub 0.03}){sub 8.2}, where {ital x}=0.23, 0.26, and 0.28, in the as-cast state and after various processing stages has been examined by optical microscopy. The size of the 2:17 matrix phase was found to be approximately 100 {mu}m in the as-cast state. A slight increase in the size of the 2:17 matrix was observed after thermal processing. Subgrains of 10 to 20 {mu}m are present in the 2:17 matrix of the fully processed ingots. Powders with a mean particle size range of 3{endash}300 {mu}m were found to exhibit a Gaussian distribution. A slight increase in intrinsic coercivity ({ital H{sub ci})} was observed when the mean particle size was decreased from 300 to 200 {mu}m and remained nearly constant for sizes ranging between 10 and 200 {mu}m. A significant decrease in {ital H{sub ci}} was observed when powders were further reduced below 10 {mu}m. Similar trends were also observed for remanence ({ital B{sub r}}), maximum energy product ({ital BH}{sub max}), and squareness of the second quadrant demagnetization curve. The size of the subgrains was found to be critical to these properties. The {ital H{sub ci}} of alloy powders with a high Fe content appeared to degrade more severely when reduced below 10 {mu}m. For a fixed mean particle size, alloy powders with a high Fe content also exhibited a less-square second quadrant demagnetization curve. A {ital B{sub r}} of 9.2 kG, {ital H{sub ci}} of 18 kOe, {ital H{sub cb}} of 7.4 kOe, {ital BH}{sub max} of 19 MGOe, and a squareness ratio of 0.91 have been obtained on Sm(Co{sub bal}Fe{sub 0.23}Cu{sub 0.08}Zr{sub 0.03}){sub 8.2}. As expected for alloys with a higher Fe content, {ital B{sub r}} of 11.3 kG, {ital H{sub ci}} of 20 kOe, {ital H{sub cb}} of 8.1 kOe, {ital BH}{sub max} of 25 MGOe, and a square ratio of 0.83 have been obtained on Sm(Co{sub bal}Fe{sub 0.28}Cu{sub 0.08}Zr{sub 0.03}){sub 8.2}. {copyright} {ital 1997 American Institute of Physics.}
- OSTI ID:
- 496614
- Report Number(s):
- CONF-961141-; ISSN 0021-8979; TRN: 97:016298
- Journal Information:
- Journal of Applied Physics, Vol. 81, Issue 8; Conference: 41. annual conference on magnetism and magnetic materials, Atlanta, GA (United States), 12-15 Nov 1996; Other Information: PBD: Apr 1997
- Country of Publication:
- United States
- Language:
- English
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