Eff ect of the overheat temperature and the cooling rate on a structure of Al-Cu system alloys

Abstract

In this paper there is examined the structural properties of Al-Cu system alloys in a solid and in a liquid state. The investigation was performed for the alloys with copper content of 25.0-34.0% (wt.), the rest is aluminum. To determine the physical properties of alloys we used microstructure analysis, X-ray structural analysis and the diff erential thermal one. We determined the phase composition of alloys in relation to the temperature of the liquid heating above the liquidus curve and to the cooling rate.
In the paper it is shown that when the temperature of the alloys liquid heating rises above the liquidus curve and reaches 150 K, both the reduction of the volume ratio of primary aluminum crystals and the increase of the eutectics volume ratio occurs. The overheating of the liquid by 200 K leads to a complete suppression of the process of formation of primary aluminum crystals, which indicates the lack of their microcomplexes in alloy liquid.

The obtained results of calculations are in good agreement with those of other authors