Mechanically alloyed Sm-(Co-Fe) permanent magnets
- Univ. of Western Australia, Nedlands, Western Australia (Australia). Research Centre for Advanced Mineral and Materials Processing
The use of mechanical alloying as a processing method for the solid-state synthesis of new materials has received considerable attention in recent years. Of particular interest has been the synthesis of rare earth permanent magnet materials. Many of the rare-earth transition metal alloys studied to date exhibit similar structures and properties in the as-milled condition. In particular, the hard magnetic phase does not form during mechanical alloying. Instead, either a single amorphous phase is formed or a two-phase mixture is developed during milling which consists of crystallites of the transition metal, (i.e. Fe, Co), and an amorphous phase containing the rare earth element. Crystallization of the as-milled structure into a nanocrystalline hard magnetic phase (i.e. Nd{sub 2}Fe{sub 14}B or SmCo{sub 5}) normally requires a heat treatment at temperatures in the range of 600--700 C. With Sm{sub 2}Fe{sub 17}N{sub 2.7}, nitriding must be carried out after crystallization since Sm{sub 2}Fe{sub 17}N{sub 2.7} decomposes to samarium nitride and {alpha}-Fe at temperatures above 500 C. Mechanically alloyed and heat treated structures have been found to exhibit remarkably high values of coercivity, H{sub c}. For example, values of H{sub c} exceeding 75 kOe have been obtained in SmCo{sub 5}.
- OSTI ID:
- 186770
- Journal Information:
- Scripta Materialia, Journal Name: Scripta Materialia Journal Issue: 1 Vol. 34; ISSN 1359-6462; ISSN XZ503X
- Country of Publication:
- United States
- Language:
- English
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