@inbook{
author = "Anđić, Zoran and Vujović, Aleksandar and Tasić, Miloš and Korać, Marija and Kamberović, Željko",
year = "2011",
abstract = "Characterization of the obtained powder indicates a possibility of the synthesis of
nanocomposite Cu-Al2O3 system by the thermochemical procedure, starting from water
solutions Cu(NO3)2 and Al(NO3)3. AEM analysis indicates the presence of individual
particles of 20-50 nm size. The shape of particles is irregular, with the presence of individual
particles of nodular shape. The surface morphology is rough. Apart from that, the presence
of an agglomerate with the magnitude of >100nm and of a sponge shape is noticeable. The
obtained nanocomposite powders, with the structure basically preserved together with the
final product, provided a significant reinforcement effect in the obtained sintered system.
This is a consequence of the homogenous distribution of the elements in the structure,
accomplished during the synthesis of powder and presence of the third phase which causes
stabilization of dislocation substructure and achieves the relevant reinforcing effect.
The analysis of the mechanical and electric properties of the sintered Cu-Al2O3 systems
based on powders obtained by the thermochemical method shows that in the system with
3wt.%Al2O3, sintered at 900ºC, structural stabilisation occurs only after 30 minutes with
considerable reinforcement effects. Since in other systems, the structural stabilisation
process was not completed even after 120 minutes, the system with 3wt.% of dispersoids
sintered at 900ºC for 30 minutes seems to be the optimum solution for the production of
dispersively reinforced Cu-Al2O3 systems. This statement is confirmed by the corresponding
analysis of the microstructure.
In accordance with the previous statements, the EDS analysis of the sintered systems surface
as well as FIB analysis show a homogenous distribution of elements, i.e. present phases. FIB
analysis also indicates the size of microstructural constituents within the range of 50-250nm.
TEM analysis of the sintered systems reveals the presence of copper crystals of 100 nm in
size exposed to twinning, thus pointing to stabilization of the dislocation substructure.
SADP of the examined nanocomposite Cu–Al2O3 sintered system shows spots and rings,
where spots refer to the individual crystals of copper, and sharp circles (rings) originate
from nanocrystals of alumina dispersed in the copper matrix. HRTEM analysis indicates the
changes in the lattice parameter, which leads to the conclusion that the eutectic reaction
occurred and the third, CuxAlyOz phase was formed on the grain boundary, which will be
the subject of future studies based on a more precise approach to physical chemistry of
system surfaces and of thermodynamic examinations of the influences of finely dispersed
Al2O3 on the formation of the third phase and the increase in the system surface energy.
In the end, all the above-mentioned examinations show that the reinforcement of Cu-Al2O3
system occurs via two mechanisms, which are: dispersion and reinforcement mechanism
due to the homogenous dispersion of fine particles of Al2O3 in the matrix, and the
mechanism of grain boundary reinforcement due to the appearance of the third phase.",
publisher = "InTech",
journal = "Nanocrystal",
booktitle = "Synthesis and Characterization of Dispersion Reinforced Sintered System Based on Ultra Fineand Nanocomposite Cu-Al2O3 Powders",
url = "https://hdl.handle.net/21.15107/rcub_cherry_5021"
}
