MICROSTRUCTURE OF AlSi17Cu5 ALLOY AFTER OVERHEATING OVER LIQUIDUS TEMPERATURE

J. Piątkowski The Silesian University of Technology, Faculty of Materials Science and Metallurgy, Katowice, Poland R. Wieszała, The Silesian University of Technology, Faculty of Transport, Katowice, Poland The paper presents microstructure tests of alloy AlSi17Cu5. In order to disintegrate the primary grain of silicon the so-called time-temperature transformation TTT was applied which was based on overheating the liquid alloy way over the temperature Tliq., soaking in it for 30 minutes and casting it to a casting mould. It was found that such process causes the achievement of fine-crystalline structure and primary silicon crystals take up the form of pentahedra or frustums of pyramids. With the use of X-ray microanalysis and X-ray diffraction analysis the presence of intermetallic phases Al2Cu, Al4Cu9 which are the ingredients of eutectics α AlCu β and phase Al9Fe2Si which is a part of eutectic α AlFeSi β was confirmed.