IJS KOLOKVIJ, ponedeljek, 09. 05. 2016; ob 13. uri; prof. dr. Kazuhiro Hono

[Tanja Debevec]

Vabimo vas na 18. predavanje iz sklopa "Kolokviji na IJS" v letu 2015/16, ki bo v ponedeljek, 09. maja 2016, ob 13. uri v Veliki predavalnici Instituta »Jožef Stefan«  na Jamovi cesti 39 v Ljubljani. Napovednik predavanja najdete tudi na naslovu http://www.ijs.si/ijsw/Koledar_prireditev, posnetke preteklih predavanj pa na http://videolectures.net/kolokviji_ijs. 

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prof. dr. Kazuhiro Hono

Magnetic Materials Unit, National Institute for Materials Science, Tsukuba, Japonska

 

 

Visokokoercitivni neodim-železo-borovi permanentni magneti brez disprozija

 

Zaradi nedavnih zadržkov glede neprekinjene preskrbe s težkimi redkimi zemljami so se številne raziskave na področju permanentnih magnetov osredotočile na neodim-železo-borove (Nd-Fe-B) magnete brez disprozija (Dy). V predavanju bomo predstavili naše nedavne dosežke pri razvoju visokokoercitivnih magnetov te vrste. Da bi dobili celovit vpogled v povezavo med mikrostrukturo in koercitivnostjo, smo nanovo raziskali mikrostrukturo Nd-Fe-B sintranih in vroče deformiranih magnetov z vrstičnim presevnim elektronskim mikroskopom (STEM) s korekcijo aberacije ter s tomografijo na atomsko sondo. Ugotovili smo, da sta struktura in kemijska sestava domenske stene odvisni od njene orientacije, tako da so stene, ki so pravokotne na c ravnine, pretežno kristalinične in imajo višjo koncentracijo Nd, medtem ko so stene, pravokotne na c ravnine, amorfne in vsebujejo večji delež Fe. Na podlagi teh odkritij smo razvili metodo za znatno povečanje koercitivnosti anizotropnih Nd-Fe-B magneto brez dodatka disprozija.  

Predavanje bo v angleščini.

Lepo vabljeni!

 

 

 




We invite you to the 18th Institute colloquium in the academic year 2015/16. The colloquium will be held on Monday May 09, 2016 at 1 PM in the main Institute lecture hall, Jamova 39, Ljubljana. To read the abstract click  http://www.ijs.si/ijsw/Koledar_prireditev. Past colloquia are posted on  http://videolectures.net/kolokviji_ijs.

 

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prof. dr. Kazuhiro Hono

Magnetic Materials Unit, National Institute for Materials Science, Tsukuba, Japan

 

 

Dy-free high coercivity Nd-Fe-B permanent magnets

 

 

Due to the recent concern about the stable supply of heavy rare earth elements, attaining high coercivity in Nd-Fe-B magnets without Dy has received intense research interest. In this talk, we will update our recent progresses toward the development of high coercivity Nd-Fe-B permanent magnets. To obtain complete understanding of the microstructure-coercivity relationships, we revisited the microstructures of Nd-Fe-B sintered and hot-deformed magnets using aberration-corrected STEM complemented by atom probe tomography. We found that the structure and chemical composition of the grain boundary phase varies depending on the orientation of grain boundaries, i.e., the grain boundary phase parallel to the c-planes are mostly crystalline with a higher Nd concentration in contrast to that lying parallel to the c-axis that contains higher Fe content with an amorphous structure. Based on these new findings, we developed a method to increase the coercivity of the anisotropic Nd-Fe-B magnets substantially without relying on Dy.  

 

Cordially invited!     

 

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