Z. Samardzija
Institut Jozef Stefan
1111 Ljubljana, Jamova 39
S. Kobe-Besenicar, IJS Ljubljana
Z metodami vrsticne elektronske mikroskopije (SEM) in energijske
in valovne disperzijske elektronske mikroanalize (EDXS, WDXS) smo
analizirali defekte v magnetih kvalitete ALNICO 1500, ki jih
proizvaja tovarna Magneti. SEM posnetki mikrostruktur kazejo na
prisotnost faz, ki se razlikujejo od matrice. Sestavo matrice smo
dolocili z EDX kvantitativno analizo. Defekte smo kvalitativno
analizirali z WDX analizo in ugotovili prisotnost lahkih
elementov: C, N, O, ki se nahajajo v vklju~kih v obliki nitridov,
karbidov ali oksidov. Na osnovi posnetkov, ki so narejeni s
karakteristicnimi rentgenskimi zarki analiziranih elementov
(mapping), smo ugotovili, da so povrsinski defekti vecinoma
oksidi titana, lahko tudi nitridi. Defekti v notranjosti matrice
ALNICO so identificirani kot titan-karbidni ali pa
karbidno-nitridni vkljucki. Analiza z elektronskim
mikroanalizatorjem omogoca kvalitativno identifikacijo defektov,
predvidevanje njihovega izvora, ter resevanje problema nastanka
defektov v proizvodnem procesu. Analiza je bistveno pripomogla k
razumevanju in definiranju razlogov za slab{e magnetne lastnosti
vzorcev, kot posledice napak v posameznih tehnolo{kih fazah v
proizvodnji.
Kljucne besede: ALNICO, elektronska mikroanaliza
Defects in ALNICO magnets, produced in Magneti factory, were
analyzed by scanning electron microscopy (SEM), energy dispersive
(EDX) and wavelength dispersive (WDX) electron probe
microanalysis. SEM micrographs of the samples showed the presence
of phases (inclusions, surface defects) which differ from the
matrix. Matrix composition was determined by quantitative EDX
analysis. Defects were analyzed qualitatively by WDX analysis
confirming the presence of light elements: C, N, O; mostly in the
form of nitrides, carbides or oxides. On the basis of
characteristic X-ray micrographs of the elements analyzed (X-ray
mapping), surface defects were identified as titanium oxides
and/or titanium nitrides. Defects inside the ALNICO matrix were
mostly titanium carbides and titanium carbo-nitrides. Electron
probe microanalysis allows qualitative identification of the
defects, prediction and determination of
their origin and
consequently the elimination of defects with the improvements in
the production process. Analysis was very useful for better
understanding of bad magnetic properties of the samples resulting
from the faults in the particular technological steps of
production process.
Key words: ALNICO, electron probe microanalysis