Refinement and thermal analysis
of hypereutectic Al-25％Si alloy
of hypereutectic Al-25％Si alloy
(The Key Laboratory of Liquid Structure and Heredity of Materials,
Ministry of Education, School of Materials Science and Engineering,
Shandong University, Jinan 250061, P.R. China)
Ministry of Education, School of Materials Science and Engineering,
Shandong University, Jinan 250061, P.R. China)
Abstract: Refinement and thermal analysis of hypereutectic Al-25%Si alloy were investigated with scanning electron microscope (SEM) and differential scanning calorimeter (DSC). The results show that the average size of primary silicon in Al-25%Si alloy without and with phosphorus addition are 250 μm and 30μm, respectively. But the primary and eutectic growth temperature is raised by about 17.3℃ and 4 ℃ respectively due to phosphorus addition. The primary nucleation temperatures are 745.0 ℃ and 762.0℃ for untreated and treated samples and in addition, the enthalpy changes of primary and eutectic transformation are -261.0 J/g and -397.3 J/g without phosphorus addition, -294.2 J/g and -386.1 J/g with phosphorus addition, respectively. Otherwise the mechanisms of refinement and thermal transformation of Al-25%Si alloy in solidifying process are also discussed.
Key words: hypereutectic Al-Si alloys; refinement; differential scanning calorimeter; enthalpy