Thermally stable, cladded permanent magnets, and compositions and methods for making the same
The disclosed technology provides a nanofunctionalized magnetic material feedstock comprising: from 50 wt % to 99.5 wt % of magnetic microparticles having an average microparticle effective diameter from 1 micron to 500 microns; from 0.4 wt % to 40 wt % of one or more rare earth elements; and from 0.1 wt % to 10 wt % of metal-containing grain-refining nanoparticles, wherein at least 1 wt % of the grain-refining nanoparticles are chemically and/or physically disposed on surfaces of the magnetic microparticles. The nanofunctionalized magnetic material feedstock is processed using high-throughput laser-based additive manufacturing to optimize the architecture of NdFeB or other magnets, generating site-specific, demagnetization-resistant microstructures. This disclosure teaches a rapid, single-step laser-based process to tailor the easy axis alignment, grain size, and microstructure of a permanent magnet at corners and edges to resist demagnetization.
1 . A nanofunctionalized magnetic material feedstock comprising:
(a) from about 50 wt % to about 99.5 wt % of magnetic microparticles having an average microparticle effective diameter from about 1 micron to about 500 microns;
(b) from about 0.4 wt % to about 40 wt % of one or more rare earth elements; and
(c) from about 0.1 wt % to about 10 wt % of metal-containing grain-refining nanoparticles having an average nanoparticle effective diameter from about 1 nanometer to about 1000 nanometers,
wherein at least 1 wt % of said metal-containing grain-refining nanoparticles are chemically and/or physically disposed on surfaces of said magnetic microparticles.
2 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said magnetic microparticles are a magnetic material selected from the group consisting of NdFeB, DyFeB, SmCo, AlNiCo, MnAl, FeN, Fe 3 O 4 , and combinations thereof.
3 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said magnetic microparticles are substantially spherical.
4 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said magnetic microparticles are non-spherical.
5 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said average microparticle effective diameter is about 100 microns or less.
6 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said average microparticle effective diameter is about 10 microns or less.
7 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said average nanoparticle effective diameter is about 100 nanometers or less.
8 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said average nanoparticle effective diameter is about 10 nanometers or less.
9 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein at least 10 wt % of said metal-containing grain-refining nanoparticles are chemically and/or physically disposed on surfaces of said magnetic microparticles.
10 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein at least 50 wt % of said metal-containing grain-refining nanoparticles are chemically and/or physically disposed on surfaces of said magnetic microparticles.
11 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein essentially all of said metal-containing grain-refining nanoparticles are chemically and/or physically disposed on surfaces of said magnetic microparticles.
12 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said metal-containing grain-refining nanoparticles form a continuous coating on said magnetic microparticles.
13 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said metal-containing grain-refining nanoparticles form a discontinuous coating on said magnetic microparticles.
14 . The nanofunctionalized magnetic material feedstock of claim 13 , wherein said discontinuous coating has a surface coverage from about 1% to about 99% on said magnetic microparticles.
15 . The nanofunctionalized magnetic material feedstock of claim 13 , wherein said discontinuous coating has a surface coverage from about 10% to about 50% on said magnetic microparticles.
16 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said nanofunctionalized magnetic material feedstock comprises at least about 1 wt % to about 10 wt % said metal-containing grain-refining nanoparticles.
17 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said nanofunctionalized magnetic material feedstock comprises at least about 5 wt % to about 10 wt % said metal-containing grain-refining nanoparticles.
18 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said one or more rare earth elements are selected from the group consisting of Dy, Pr, Tb, Ce, and Nd.
19 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said one or more rare earth elements are alloyed with Cu in the form of a eutectic mixture, and wherein said Cu is not counted toward the concentration of said one or more rare earth elements in said nanofunctionalized magnetic material feedstock.
20 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said metal-containing grain-refining nanoparticles are a zirconium-containing material selected from Zr, ZrC, ZrB 2 , ZrH 2 , ZrO 2 , Zr 2 O 3 , or a combination thereof.
21 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said nanofunctionalized magnetic material feedstock further comprises a magnetic nanomaterial selected from the group consisting of NdFeB, DyFeB, SmCo, AlNiCo, MnAl, FeN, Fe 3 O 4 , and combinations thereof.
22 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said nanofunctionalized magnetic material feedstock further comprises a grain-growth-restriction agent selected from Cu, B, or a combination thereof.
23 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said nanofunctionalized magnetic material feedstock further comprises a grain-boundary modifier selected from the group consisting of Dy 2 O 3 , Cu, Nd, and combinations thereof.
24 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said nanofunctionalized magnetic material feedstock further comprises an electrical-resistivity modifier selected from the group consisting of Dy 2 O 3 , Al 2 O 3 , Zr 2 O 3 , ZrO 2 , Y 2 O 3 , Ce 2 O 3 , CeO 2 , AlN, SiO 2 , TiB 2 , TiC, ZrB 2 , ZrC, and combinations thereof.
25 . The nanofunctionalized magnetic material feedstock of claim 1 , wherein said nanofunctionalized magnetic material feedstock further contains one or more functional additives.