At the present work, experiments were made with the unrefined alloy Al –
0,6%Mg - 0,8%Si, with variations in copper content (0,05% e 0,3%), that aimed to
evaluate two aspects of the alloy behavior. The first aspect concerns the affinity
between it and the mold, which seeks to observe the effect of the solidification
thermal variables of the structure of molten and the correlation with mechanical and
electrical properties, the second aspect is related with the intrinsic behavior of the
variation on the chemical composition subject at low speed and cooling rates. For
evaluating the solidification thermal variables (liquidus isotherms velocities, cooling
rates) was used a device for horizontal unidirectional solidification. The ingots
produced from the solidification of the alloy rose by mechanical machining,
laminating and steel drawing, examined in different positions and diameters, by
testing the traction and electric conductivity. Fractures were analyzed in terms of
micro cavities and different levels of copper and it was found that in the cold
deformed material, the limit of tensile strength has a trend of growth for the alloys of
higher concentration of copper. The measured values have also concluded that the
electrical conductivity increases the greater the diameter of the micro cavities and
lower the copper content. In order to evaluate only the intrinsic variation behavior of
the alloy chemical composition, a second device was used for solidification, mold in
"U", painted internally in solution of kaolin that attaches to such low rates of cooling.
The results show that for both copper content there is a tendency of increase in the
limit of tensile strength with increasing reduction suffered by the samples, the limit of
tensile strength greater for the alloy with higher copper content. We attach this
behavior to the higher content of solute which in turn showed better response to
plastic deformation, compressing the material. However, the electrical
characterization occurs in an opposite way, as seen in unidirectional solidification,
where the lowest copper content was more efficient.
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