摘要
The effect of Sr on modification and refinement of the Mg 2 Si phase in an AZ61-0.7Si magnesium alloy has been investigated and analyzed.The results indicate that Sr can effectively modify and refine the Chinese-script shaped Mg2Si phase in the AZ61-0.7Si alloy.By adding 0.06wt.%-0.12wt.%Sr to AZ61-0.7Si alloy,the Mg2Si phase in the alloy can be changed from the initial coarse Chinese-script shape to fine granule and/or irregular polygonal shapes.Accordingly,the Sr-containing AZ61-0.7Si alloy exhibits higher tensile and creep properties than the AZ61-0.7Si alloy without Sr modification.The mechanism on modification and refinement of the Mg2Si phase in Sr-containing AZ61-0.7Si alloy is possibly related to the following two aspects:(1)adding Sr may form the Al4Sr phase which can serve as the heterogeneous nucleus for the Mg2Si particles and/or(2)adding Sr may lower the onset crystallizing temperature and increase the undercooling level.
The effect of Sr on modification and refinement of the Mg2Si phase in an AZ61-0.7Si magnesium alloy has been investigated and analyzed. The results indicate that Sr can effectively modify and refine the Chinesescript shaped Mg2Si phase in the AZ61-0.7Si alloy. By adding 0.06wt.%-0.12wt.%Sr to AZ61-0.7Si alloy, the Mg2Si phase in the alloy can be changed from the initial coarse Chinese-script shape to fine granule and/or irregular polygonal shapes. Accordingly, the Sr-containing AZ61-0.7Si alloy exhibits higher tensile and creep properties than the AZ61-0.7Si alloy without Sr modification. The mechanism on modification and refinement of the Mg2Si phase in Sr-containing AZ61-0.7Si alloy is possibly related to the following two aspects： （1） adding Sr may form the Al4Sr phase which can serve as the heterogeneous nucleus for the Mg2Si particles and/or （2） adding Sr may lower the onset crystallizing temperature and increase the undercooling level.
基金
supported by the National Natural Science Funds for Distinguished Young Scholar in China(No.50725413)
the Major State Basic Research Development Program of China(973)(No.2007CB613704)
the Natural Science Foundation Project of CQ CSTC(No.2007BB4400)
Chongqing Science and Technology Commission in China(No.2006AA4012-9-6).
