Inclusion measurements in Al–6Si alloys using liquid metal cleanliness analyser technique

Abstract

The present study was undertaken to investigate the capability of the liquid metal cleanliness analyser (LiMCA) technique for measuring different types of inclusions in commercial pure aluminium and Al–6Si casting alloys. The main purpose of the study was to evaluate the technique in the case of casting alloys, where the inclusion levels are considerably higher than those found in wrought aluminium alloys for which the LiMCA has generally been used to date. The inclusion types studied included Al2O3, Al4C3, MgO, CaO, TiB2 and TiAl3, representing inclusions typically found in aluminium casting alloys. The inclusion additions were made using powder, master alloy, pure metal and metal matrix composite sources. In the case of powder inclusions, the inclusions were injected into the alloy melt using a powder injection technique to prepare inclusion containing ingots, which were subsequently used for inclusion addition to fresh alloy melts to conduct the LiMCA tests. Microstructural examination of solidified samples obtained from the LiMCA probe tube used for the measurements and from samplings of the melt was also carried out using optical microscopy and electron probe microanalysis.