利用光学显微镜(OM)、扫描电子显微镜(SEM)、X 射线衍射仪(XRD)分析了 Li 元素对 Mg-x Li-3Al 合金组织的影响,并用电子万能试验机测试合金的拉伸性能.结果表明,Li 含量的变化可以明显改变合金的相组成.当 m (Li)＜5．7％(质量分数)时合金由单一α-Mg 相组成；Li 含量在5．7％~10．3％(质量分数)之间时,合金为α-Mg＋β-Li 双相；m (Li)＞10．3％(质量分数)时合金为单一β-Li 相.合金的塑性随 Li 含量的升高而增加,铸态 LA113合金的延伸率高达37．36％,但挤压态下合金强度随 Li 含量升高而降低,挤压态 LA53合金具有最佳抗拉强度,达到263．28 MPa.当 Li 含量升高,合金中的第二相粒子会出现 Al12 Mg17转变为 LiMgAl2.%Effects of Li addition on the microstructure of Mg-3Al based alloys were studied by optical microscope (OM),scanning electron microscope (SEM)and X-ray diffractometer (XRD).The tensile properties of as-cast and as-extruded Mg-x Li-3Al alloys were conducted at ambient temperature on an electro-universal testing ma-chine (Instron 5569).The results show that lithium content in Mg-Li alloy was a key factor affecting the micro-structure and properties of this series alloys.When it was between 5.7%-10.3wt%,Mg-Li alloy exhibits two phases structure which consists of α (hcp)Mg-rich and β (bbc)Li-rich phases.The elongation of alloys im-proves significantly with the increase of Li content and the as-cast LA1 13 alloy obtains the optimal elongation of 37.36%.But the tensile strength of as-extruded Mg-x Li-3Al alloys decrease with the increase of Li content and the as-extruded LA53 alloy obtains the optimal tensile strength of 263.28 MPa.As Li content increases,the sec-ond-phase particle Al1 2 Mg1 7 transforms into LiMgAl2 in Mg-Li alloys.
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