Thermal analysis and microscopical characterization of Al–Si hypereutectic alloys

In this research paper are presented the identified phases by thermal analysis and microscopy presented by four 3XX.X Al–Si hypereutectic alloys that were solidified under different conditions including natural heat exchange and quenching. In addition, a qualitative analysis of the phases was conducted by EDX scanning electron microscopy. The EDX results were used to identify the stoichiometry for the particular phases based on data reported in the literature. A total of nine reactions were detected by thermal analysis that were confirmed by optical and electron microscopy, where two additional phases (Fe and Pb enriched) were also detected. Above the liquidus temperature, the phase known as Si agglomerates was identified; the nature and principal characteristics of this phase are discussed in the present paper. Using thermal analysis, the phase identification, fraction solid and nucleation temperature for all the phases was conducted.