Microstructure and Hard Magnetic Properties of Sm1-xZrx(Fe,Co)11.3-yTi0.7By Ingots and Thick Melt-Spun Ribbons
- Univ. of Delaware, Newark, DE (United States)
Permanent magnets made from Sm(Fe,Co)12-based compounds are being actively pursued through nanostructuring and powder metallurgy. This study was aimed at the development of hard magnetic properties in bulk as-cast alloys and in melt-spun alloys for very low wheel speeds. Slower solidification rates and alloying with Zr promote the tetragonal ThMn12-type crystal structure, whereas higher solidification rates and alloying with B replace the ThMn12 structure type with the TbCu7 structure type. When introduced simultaneously, Zr and B dramatically reduce the alloy solidification rates required for both the refinement of the 1:12 crystallites and their replacement with the 1:7 phase. In bulk arc-melted alloys, this allowed for a microstructure of separated 1:12 crystallites 1–3 μm in size, although, because of the ferromagnetic nature of a minority phase, the coercivity of these fine-grained alloys reached only 0.73 kOe. A moderately accelerated solidification further refined the 1:12 crystallites and increased the coercivity; a Sm0.7Zr0.4(Fe,Co)10.8Ti0.7B0.5 alloy exhibited a coercivity of 1.5 kOe and a maximum energy product of 3.4 MGOe when it was melt-spun into a 0.26-mm-thick ribbon. A more rapid solidification suppressed the 1:12 phase and after annealing at 800–850 °C, the alloys modified with Zr and B developed reasonably high coercivity and maximum energy product even when melt-spun at a wheel speed of 6 m/s. For the above-mentioned alloy, these values were 4.1 kOe and 7.8 MGOe, respectively. Further, a similarly processed very-Sm-lean Sm0.5Zr0.6(Fe,Co)10.6Ti0.7B0.7 alloy exhibited a remanence of 8.8 kG and an energy product of 7.4 MGOe.
- Research Organization:
- Univ. of Delaware, Newark, DE (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- FG02-90ER45413
- OSTI ID:
- 1812306
- Journal Information:
- IEEE Transactions on Magnetics, Vol. 58, Issue 2; Conference: Intermag 2021, Lyon (Held Virtually) (France), 26-30 Apr 2021; ISSN 0018-9464
- Publisher:
- Institute of Electrical and Electronics Engineers. Magnetics GroupCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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