Efeito da Taxa de Resfriamento nas Propriedades Mecânicas e nas Características Macro e Microestrurutrais da Liga Al-4,5%Cu Solidificada Radialmente

Abstract

Various, industrial sectors, which are products of high mechanical strength and specific low weight, such as the automotive and aeronautical sector, make use of alloys of the Al-Cu system. The vast use in applications techniques is justified by the fact that aluminum alloys may have their mechanical properties altered in function of their own chemical structure, by altering the copper content and / or by the addition of alloying elements, or , by means of the strict control of the cooling rates during the solidification of the components. In this work, a comparative study was performed between the mechanical properties and the macro and microstructural characteristics of Al-4.5% Cu alloy by weight when subjected to different unidirectional solidification conditions. For this, tests of hardness, microhardness, density quantification, chemical analysis by x-ray fluorescence and metallographic analyzes were performed. In view of the obtained results, the strong influence of the cooling rate on the mechanical properties and the microstructure of the alloy is evident, so that as the cooling rates increase, the dendritic spacings decrease and the microhardness values increase. In addition, the amount of shrinkage defects and microporosities increased with increasing cooling rate, resulting in a decrease in hardness values.