Avaliação da eficácia da técnica de difração de raios-X para caracterizar fases presentes em dois ferros fundidos cinzentos perlíticos com diferentes adições de nióbio.
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Date
2021
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Abstract
This work aims to present a brief state of the art regarding the characterization
techniques currently used to evaluate the effects of fabrication processes on the structure
of gray cast iron, as well as to evaluate the effectiveness of the X-ray diffraction technique
(XRD) to identify and quantify the phases present in two types of gray cast iron: one with
low (0.02% by weight) and the other with high niobium content (0.21-0.24% by weight).
For both samples, the three main phases were identified: graphite-G, ferrite-Fe(α) and
cementite-Fe3C. However, not even for the sample with the highest niobium content,
niobium carbide (NbC) was identified by this technique, a fact justified by the detection
limit of the conventional diffractometer used and the small fraction of this carbide in the
analyzed samples. The modification in the niobium concentration was not enough to
promote significant differences in the diffractograms. The fluorescence of iron excited
mainly by Cu Kα radiation resulted in a high level of noise in the measurements and made
it impossible to quantify the phases by means of Rietveld refinement. Thus, for the
analyzed niobium contents and limitations of the instrumental conditions used in this
work to minimize these iron fluorescence effects in the samples (but usual operating
conditions of copper tube equipment in routine operation), it is concluded that the Cu
tube XRD technique is not effective for quantifying phase fractions nor for identifying
NbC in gray cast iron.
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Keywords
Nióbio, Difração de raios-X, Gray cast iron, Niobium, Phases
Citation
REIS, B. C. M. et al. Avaliação da eficácia da técnica de difração de raios-X para caracterizar fases presentes em dois ferros fundidos cinzentos perlíticos com diferentes adições de nióbio. Journal of Experimental Techniques and Instrumentation, v. 4, p. 81-91, 2021. Disponível em: <https://periodicos.ufms.br/index.php/JETI/article/view/13153>. Acesso em: 29 abr. 2022.