(太原理工大學 材料科學與工程學院，太原 030024)
摘 要: 采用OM、XRD、SEM和EDS研究不同Sr含量對AM80合金微觀組織與力學性能的影響。結果表明，Sr在晶界處發(fā)生偏聚，使晶粒長大受阻，從而細化α-Mg基體，Sr在枝晶尖端的富集改變了初生相α-Mg的形貌。隨Sr含量增加，出現新相Al4Sr，β-Mg17Al12相含量不斷降低直至完全消失。添加Sr可使AM80鎂合金的室溫力學性能得到明顯改善，添加1.5%Sr(質量分數)時效果最好，其抗拉強度和伸長率分別達到最大值160 MPa和15.04%。隨Sr含量的增加，AM80鎂合金斷裂方式由解理斷裂向韌性斷裂、再向解理斷裂方式轉變。
關鍵字: 鎂合金；Sr；顯微組織；力學性能
（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
