Changes in the Structure of the AK7 Alloy in Terms of Modification

Abstract

On this work there was decided to verify the possibility of influence of micro additives of strontium and boron on structure of AlSi7Mg (EN-AC-42000) alloy with chemical composition according to PN-EN 1706. As the modifier there were used AlSr10 (0.3%) and AlTi5B1 (0.3%) master alloy, which were added separately and together. Changes in the structure of individual samples of the AK7 alloy were examined using a metallographic microscope. The chemical composition of complex intermetallic phases formed in the structure of the tested alloy was also examined. The most beneficial effect turned out to be the effect of strontium in the form of 0.3% AlSr10, ensuring a favourable conversion of lamellar silicon into the form of fine fibres. The presence of complex phases was observed in all test samples. Most often, these were phases with various needle shapes and variable Fe and Mn contents.