Effect of Sc Additions on the Modification of Eutectic Si of As Cast Al-9wt%Si Alloy

The demand for high–strength castings at competitive prices, for applications where the ratio strength/unit mass is a critical factor, such as automotive and aeronautics, has increased exponentially. Among the aluminum casting alloys stand out the Al-Si alloys (with or without Cu and/or Mg additions), which represent 80% of aluminum casting alloys. One of the microstructural parameters that most influence the properties of Al-Si alloys is the morphology (volume fraction, size, shape and distribution) of eutectic silicon. The modification of the eutectic can be obtained by chemical modification by the addition of several elements [1,2]. It was recently reported that some transition metals can promote the modification of the eutectic, among which stands out scandium (Sc) [3]. The addition of scandium to aluminum alloys has been the subject of several studies in recent years, since the addition of small amounts induces a significant increase in the mechanical properties of these alloys.