Mechanically strengthened heterogeneous Sm-Co sintered magnets

Journal Article · 25 January 2022 · Journal of Alloys and Compounds

DOI: https://doi.org/10.1016/j.jallcom.2022.163937 · OSTI ID:1846442

Cui, Baozhi ^[1]; Liu, Xubo ^[1]; Nlebedim, Cajetan I. ^[1]; Cui, Jun ^[2]

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1. Ames Lab., Ames, IA (United States)
2. Ames Lab., Ames, IA (United States); Iowa State Univ., Ames, IA (United States)

Samarium-cobalt sintered magnets offer excellent magnetic properties, thermal stability, and corrosion resistance. They are used in a variety of defense and civilian applications, especially when elevated operation temperatures (e.g., 200 ºC to 550 ºC) are required. However, the utilization of these materials is restricted by their brittleness. Improving their mechanical resilience would make them more cost-effective, efficient, and robust in decarbonization and other function-related applications while reducing the pressure on critical material supply chains. In this paper, we engineer a series of novel heterogeneous microstructures, such as laminated coarse grain (CG)/fine grain (FG) and core/shell CG/FG microstructures, to produce unprecedented combinations of superior mechanical and magnetic properties without altering the chemical compositions of the magnets or common heat treatment procedures. Further, a 60% flexural strength enhancement is obtained using heterogeneous Sm₂(CoFeCuZr)₁₇ sintered magnets with little impact on their magnetic properties. The mechanically robust heterogeneous Sm-Co sintered magnets have a minor (e.g., less than 4.6%) reduction in the energy product (BH)_max due to a slightly reduced squareness of the demagnetization curve, with no decrease in either the remanence (B_r) or the intrinsic coercivity (H_ci). The flexural strengths of these heterogeneous Sm-Co magnets depend on the volume ratios and mean grain sizes of the FG/CG regions, as well as their microstructural architectures. The fine-grained regions act as mechanical strengthening sites, which can be strategically used when designing the magnet for different applications. This technology is highly compatible with existing magnet manufacturing processes and thus can be adopted readily by the magnet industry.

• Research Organization: Ames Laboratory (AMES), Ames, IA (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-07CH11358
• OSTI ID: 1846442
• Report Number(s): IS-J-10,719
• Journal Information: Journal of Alloys and Compounds, Journal Name: Journal of Alloys and Compounds Vol. 904; ISSN 0925-8388
• Publisher: ElsevierCopyright Statement
• Country of Publication: United States
• Language: English