(太原理工大学 材料科学与工程学院，太原 030024)
摘 要: 采用OM、XRD、SEM和EDS研究不同Sr含量对AM80合金微观组织与力学性能的影响。结果表明，Sr在晶界处发生偏聚，使晶粒长大受阻，从而细化α-Mg基体，Sr在枝晶尖端的富集改变了初生相α-Mg的形貌。随Sr含量增加，出现新相Al4Sr，β-Mg17Al12相含量不断降低直至完全消失。添加Sr可使AM80镁合金的室温力学性能得到明显改善，添加1.5%Sr(质量分数)时效果最好，其抗拉强度和伸长率分别达到最大值160 MPa和15.04%。随Sr含量的增加，AM80镁合金断裂方式由解理断裂向韧性断裂、再向解理断裂方式转变。
关键字: 镁合金；Sr；显微组织；力学性能
（School of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, China）
Abstract:The effects of Sr addition on the microstructure and mechanical properties of AM80 magnesium alloy were investigated by optical microscopy (OM), X-ray diffractometry (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The results indicate that the segregation of Sr element at solidification interface front leads to the grain refinement and the blunting of α-Mg dendrite. With increasing the Sr content, new phases Al4Sr can be observed. Meanwhile, the amount of β-Mg17Al12 phase decreases. The addition of Sr can modify the mechanical properties of AM80 magnesium alloy obviously at room temperature. Among the Sr-containing alloys, the alloy with the addition of 1.5%Sr (mass fraction) exhibits relatively optimal mechanical properties，and the tensile strength and elongation reach the maximum values of 160 MPa and 15.04%. As the Sr content increases, the fracture mechanism of the AM80 alloy at room temperature changes from cleavage fracture to ductile fracture, and then to the cleavage fracture mode.
Key words: magnesium alloy; Sr; microstructure; mechanical properties
