中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 11 No. 3 June 2001 |
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）
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
