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| Feasibility Study of HDDR and Mechanical Milling Processes for Preparation of High Coercivity SmCo5 Powder |
| Journal of Magnetics, Volume 8, Number 3, 30 Sep 2003, Pages 124-127 |
H.W. Kwon*  (School of Materials Science and Engineering, Pukyong National University) |
| Abstract |
| HDDR (hydrogenation, disproportionation, desorption, recombination) and mechanical milling processes have been applied to the SmCo5 alloy in an attempt to produce a highly coercive powder. The SmCo5 alloy had very high structural stability under the hydrogen atmosphere and the 1:5 phase was only partially disproportionated under up to 10 kgf/cm2 hydrogen gas. The partially disproportionated material was recombined not into 1:5 phase after the HDDR, but rather into multi-phase mixture consisting of 1:5, 2:17, 2:7 and 1:7 phases. The SmCo5 alloy HDDR-treated with hydrogen up to 10 kgf/cm2 had poor coercivity. For a useful HDDR to prepare a high coercivity SmCo5 alloy powder, much higher hydrogen pressure well exceeding 10 kgf/cm2 would be required. The SmCo5 alloy lump was amorphized by an intensive mechanical milling, and it was crystallised ultra-finely by a subsequent optimum annealing. The optimally annealed material had very high coercivity, and it was found that the mechanical milling followed by an annealing was an effective way of producing highly coercive SmCo5 alloy powder. |
| Keywords: SmCo_5; HDDR; hydrogenation; disproportionation; desorption; recombination; mechanical milling |
| DOI: |
| Full Text: PDF |
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