中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
Vol. 17 Special 1 November 2007 |
(Key Laboratory of Automobile Materials of Ministry of Education,
Department of Materials Science and Engineering, Jilin University, Changchun 130025, China)
Abstract:The Y2O3 addition to Mg-5Si alloys has a good modification effect on the primary Mg2Si. With 0.05% or 0.1% (mass fraction) Y2O3 additions, the primary Mg2Si begins to change from coarse dendritic shape (about 100 mm) into small polyhedral shape and therefore the alloys exhibits sub-modified microstructure. With 0.2% Y2O3 addition, most of the primary Mg2Si becomes polyhedral shape and its average size is only 25 mm or less. The Mg-5Si alloy exhibits modified microstructure. In addition, the experiments show that the reaction between Mg and Y2O3 cannot occur in the sintered Mg-6Y2O3 compact; however, the reaction among Mg, Si and Y2O3 can occur in the sintered Mg-5Si-6Y2O3 compact. Apart from the adsorption and poisoning manners, other mechanisms may exist in the modification of Y2O3 addition on the primary Mg2Si.
Key words: microstructure; solidification; Mg2Si; Y2O3; Mg-5Si alloy