Evaluation of the LiMCA II technique for inclusion measurements in pure aluminum and aluminum-6%silicon cast alloys: Role of melt temperature

Aluminum-silicon (Al-Si) based casting alloys constitute the majority of aluminum castings, due to the high fluidity provided by the presence of a relatively large volume of the Al-Si eutectic. The demand for higher quality aluminum cast products, particularly in the automotive and aerospace industries, has focused much attention on the quality of molten aluminum. Metal cleanliness, an important characteristic that affects the quality and performance of the final product, is determined by the amount of trace elements, gases, oxides, impurities and inclusions present in the melt. Inclusions in aluminum alloy castings have been a major problem in process and quality control.; Control of metal cleanliness in molten Al-Si alloys requires the means to monitor and minimize the presence of impurities, inclusions and gases. Many techniques have been introduced to measure the inclusion content in aluminum melts. Among them, the LiMCA (Liquid Metal Cleanliness Analyzer) technique is a non-destructive technique that is capable of carrying out in situ measurements of the inclusion concentrations and distinguishing them according to the particle size.; The present study was undertaken to investigate the capability of the LiMCA technique for measuring different types of inclusions in commercial pure aluminum and Al-6%Si casting alloys, under low (680 °C) and high (750 °C) melt temperature conditions. 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 aluminum alloys for which the LiMCA has generally been used to date. (Abstract shortened by UMI.)...