Estudo de um compósito Nb-15%pCu obtidos por moagem de alta energia e sinterizados por fase líquida
There is great difficulty in forming a composite refractory metal niobium with copper. This is due to the fact that Nb-Cu system is almost mutually immiscible and may be neglected solubility between them. These properties hinder or prevent obtaining homogeneous and high-density structures, conven...
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| Formato: | Dissertação |
| Idioma: | por |
| Publicado em: |
Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/19594 |
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| Resumo: | There is great difficulty in forming a composite refractory metal niobium with
copper. This is due to the fact that Nb-Cu system is almost mutually immiscible and may
be neglected solubility between them. These properties hinder or prevent obtaining
homogeneous and high-density structures, conventionally prepared. This study aims to
analyze the use of high-energy milling process (MAE) to implement these natural
difficulties, with regard to the densification of the sintered bodies. The MAE and the press
were used in the preparation of powders, to obtain a fine and homogeneous distribution
of the grain size. Four loads Nb and Cu powders containing 15% by weight of Cu were
then milled for MAE in a planetary type ball mill under various milling times and speeds.
The results obtained by MAE were analyzed by scanning electron microscopy (SEM),
according to the parameters of time and grinding speed. The samples were compacted
under pressure of 200 MPa, were then sintered in liquid phase in a vacuum furnace at
temperatures of 1100 ° C / 60 min and 1200 ° C / 60 min. Then it was used to characterize
diffraction of X-rays to identify the phases. The microstructures of the sintered samples
were observed and evaluated using scanning electron microscopy (SEM). Vickers
Microhardness tests were performed, obtaining higher values for the sintered bodies in
the largest of the post milling times and the larger grinding speeds. It was found that the
liquid phase sintering of the samples that were processed by MAE produced at the end of
a homogeneous and densified structure in 77,4% relative to the value of the theoretical
density of the composite |
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