铸态Mg-Li-Al-xSi合金微观组织和力学性能（英文）

Microstructure and Mechanical Properties of as-Cast Mg-Li-Al-xSi Alloys

实验铸造了Mg-9Li-3Al-x Si(x=0,0.1,0.5,1.0,质量分数,%)合金并通过OM,SEM,XRD和力学性能测试对其进行了研究。结果表明:铸态Mg-9Li-3Al合金组织中主要由α-Mg、β-Li、Mg_(17)Al_(12)相组成。加入Si后,合金中出现了新相Mg2Si,晶粒得到了明显细化,且Si能够抑制Mg_(17)Al_(12)的形成;当合金中的Si含量过高时,α-Mg相粗化,且会在相界处出现块状和汉字状的Mg_2Si相。合金的强度随着Si含量的增加呈现先增加后降低的趋势,合金的延伸率随着Si含量的增加呈现逐渐降低的趋势。当合金中Si含量为0.1%时,抗拉强度达到最大值182.5 MPa,延伸率为12.1%。

As-cast Mg-9Li-3Al-xSi（x=0, 0.1, 0.5, 1.0, wt%）alloys were prepared and then investigated by optical microscope（OM）, scanning electron microscope（SEM） and X-ray diffractometer（XRD） and mechanical properties test. Results show that the as-cast Mg-9Li-3Al alloy consists of α-Mg, β-Li and Mg（17）Al（12） phases. The addition of Si leads to the formation of new phase（Mg2Si） and the refinement of the grain size. Moreover, Si addition can restrain the formation of Mg（17）Al（12）. However, when the content of Si is excessive, α-Mg phase will be coarsened and Chinese script Mg2 Si phase is formed in the phase boundary. The tensile strength of alloys initially increases and then decreases while the elongation decreases monotonically with the increase of Si content. Specifically, as-cast Mg-9Li-3Al-0.1Si shows a favorable combination of ductility and strength with an ultimate tensile strength of 182.5 MPa, yield strength of 136.8 MPa, and an elongation of 12.1%.