Tailoring of the magnetic properties of SmCo/sub 5/:Nb/sub 0.33/Cr/sub 0.67/ nanocomposites using mechanical alloying

Abstract

Nanocomposite structures composed of ferromagnetic particles dispersed in a matrix are systems in which the magnetic properties can be tailored by varying the size and spacing of the ferromagnetic particles. Nanocompo$i~es of SmCos in a non-magnetic Nb0.dk8.67 matrix exhibit a wide variety of magnetic properties. SmCos powder is premilled prior to mechanical alloying. The premilliing results in a maximum coercivity of 16 kOe after 2 hours of milling, and an enhanced remanence ratio. Both features may be due to exchange anisotropy and/or exchange coupling between hard and soft ferromagnetic phases. The nanocomposite samples show that, when the SmCos particulates are small enough, the primary effect of alloying is to disperse them throughout the matrix with no further refinement of size.

Magnetic Properties of Nanostructured Materials

“…169,[257][258][259][260][261][262][263] Subsequent studies focused on Sm(Fe,X) 12 , 264 (Sm,Zr)Fe 3 , 265 Sm 2 -Fe 17 N x , [266][267][268] FeZr, 269 and CoNbB. 270 Similar structures optimized for high remanence and coercivity have been formed by in the SmCo family by mechanical alloying, 225,[271][272][273] and in sputtered SmCo/CoFe multilayers. 274 In 1991, Kneller and Hawig 275 suggested that anisotropy could be transmitted across hard and soft magnetic phases via exchange coupling.…”

“…The first experimental observations were in Nd 2 Fe 14 B compounds, which exhibited remanence ratios up to 0.9. ,− Subsequent studies focused on Sm(Fe,X) 12 , (Sm,Zr)Fe 3 , Sm 2 Fe 17 N x , − FeZr, and CoNbB . Similar structures optimized for high remanence and coercivity have been formed by in the SmCo family by mechanical alloying, ,− and in sputtered SmCo/CoFe multilayers . In 1991, Kneller and Hawig suggested that anisotropy could be transmitted across hard and soft magnetic phases via exchange coupling.…”

Direct chemical synthesis of high coercivity air-stable SmCo nanoblades

“…Rare earth-transition metal ͑RE-TM͒ compounds with iron or cobalt as the TM constituent and one of the magnetic light REs, i.e., Pr, Nd, or Sm, as the RE constituent are especially well-suited for use as high-temperature, highperformance permanent magnets. [1][2][3][4][5][6][7][8][9][10][11][12] In the RE-TM intermetallic compounds, the RE unpaired 4f electrons provide the magnetocrystalline anisotropy, which is potentially much stronger than the shape anisotropy, whereas the TM 3d electrons provide most of the magnetization and determine the Curie temperature. The Sm-Co binary equilibrium phase diagram indicates seven intermetallic compounds ͑RE:TM ratios 2:17, 1:5, 2:7, 1:3, 1:2, 9:4, and 3:1͒ that are stable under standard atmospheric conditions.…”

Interface engineering in ferromagnetic high-thermal conductivity iron-diamond/metal composites for electric conversion applications

“…Composite materials with ferromagnetic properties have been since long fabricated by incorporating ferromagnetic materials as finely divided inclusions (like iron powders or fibers [2,4], barium ferrites [4], strontium particles [6], flakes of Fe-Cr [7], SmCo5 [8], iron nitride [9], iron oxide [10], CoFe [11] and ferrites [12,13]) into different non-magnetic metal matrices (Zn-22Al, Cu-ZnAl, Nb 0.33 Cr 0.67 , silver and copper). These soft magnetic powder-based composites (FPC), often fabricated by the established procedures of powder packing and ulterior densification by liquid infiltration with an appropriate matrix, were firstly developed aiming to replace some steel parts, subjected to time-varying magnetic fields, in electromagnetic devices of high power converter units and electric motors [1][2][3][4][5].…”