Tuesday, May 17, 2011

Acronym in materials science: NIB for neodymium-iron-boron

In materials science and engineering, the acronym NIB stands for three chemical elements: neodymium-iron-boron. The reason for grouping these three elements together is that they can be alloyed into strong magnets with an energy product of about 470 kJ·m-3 [1].

NIB-based alloys belong to a particular material class which is critical to the design of rare-earth magnets and named rare-earth iron alloys, typically referring to alloys with a composition of two rare earth atoms to 14 iron atoms and one boron atom [2].

In NIB the rare-earth element is neodymium, which may partially be substituted by dysprosium to obtain magnets for high-temperature applications, for example, in car engines. 
Change of chemical composition, by including other element types and varying atomic ratios, results in alloys with different magnetic properties (see Table IV-1 in [2]). In addition to dysprosium, samarium and praseodymium are used.

Iron atoms in NIB-based alloys have been substituted by copper, cobalt, zirconium and hafnium atoms. Corresponding energy products range from 130 to 400 kJ·m-3. But much higher values are desired for green technologies. A nanostructured, multilayered material composed of alternating Sm2Fe17N3 and Fe65Co35 layers can theoretically reach an energy product close to 1 MJ·m-3 [3]. But current technology has not yet reached the stage of fabrication to get magnets with energy products that come anywhere near this upper boundary.

References and detailed information
[1] Nicola Jones: The Pull of Stronger Magnets. Nature, April 7, 2011, 472 (7341), pp. 22-23. DOI: 10.1038/472022a.
[2] Magnetic Materials Producer Association: Standard Specifications for Permanent Magnet Materials [www.intl-magnetics.org/pdfs/0100-00.pdf].
[3] Ralph Skomski and J. M. D. Coey:  Giant energy product in nanostructured two-phase magnets. Phys. Rev B. 1993, 48 (21), pp. 15812-15816. DOI: 10.1103/PhysRevB.48.15812.

1 comment:

  1. Nice information..