Rapidly solidified Sm–Co–V nanocomposite permanent magnets

Abstract

Alloys around the Sm-Co eutectic composition provide an opportunity to form two-phase nanocomposite permanent magnets consisting of nanoscale Co fibers embedded in Sm 2 Co 17 .While ternary alloying elements may refine the scale of the structure, they may also disrupt the eutectic growth and lead to the formation of primary Co. Thus, microstructural selection maps were constructed for conventionally solidified Sm-Co-V alloys. It was found that V additions enlarged the primary Sm 2 Co 17-forming region and, at ͑Sm 0.09 Co 0.91 ͒ 97 V 3 , resulted in a eutectic structure. Upon rapid solidification, this alloy was determined to have a coercivity of 5 kOe with a high remanent ratio. However, the V addition reduced the magnetization, which limited the energy product to 4.3 MG Oe. The rapidly solidified structure consisted of primary SmCo 7 dendrites along with an intergranular Co region, suggesting that eutectic structure formation is skewed by underlying metastable phase relationships.

Structural and magnetic properties of Sm(Co0.7Fe0.1Ni0.12Zr0.04B0.04)7.5 melt spun isotropic and anisotropic ribbons

“…The best sample retains a coercivity of 5 kOe at 380 °C. Moreover, the discussed maximum energy product in Ref [29] -and Ref [30] thereinwhich is associated to this research work was increased notable, more than 70 %, though the anisotropic treatment. …”

“…The lattice parameters for the 1:7 (SmCo 7 ) phase are determined as a=b≈4.95 Å, c≈4.07 Å after Rietveld analysis. The diffraction peaks (111), (200) and (220) of fcc-Co for λ (Fe-Kα) correspond at angles ~56 o , ~66 o and ~101 o , respectively and they can vaguely be seen in some as-spun diffraction patterns [30].…”

Microstructural selection in conventionally and rapidly solidified Sm–Co–T alloys

“…However, the ternary alloying elements may significantly influence both the stability of the eutectic growth front and phase selection upon solidification. Previously, we observed a eutectic structure in ternary Sm-Co-V alloys [13]. Here, we further explore this system, as well as others, specifically related to developing microstructural selection maps.…”