Li含量对Mg-8Gd-2Y-0.6Zr合金组织与力学性能的影响

Effect of Li on microstructures and mechanical properties of Mg-8Gd-2Y-0.6Zr alloys

通过对不同Li含量的Mg-8Gd-2Y-0.6Zr镁合金进行熔炼、制坯和反向挤压,研究了Li含量对其合金组织及力学性能的影响。结果表明:Mg-8Gd-2Y-0.6Zr镁合金中Li添加1.5wt.%左右时,Li主要固溶在α-Mg中或以Mgx(Gd,Y,Li)y化合物相析出;当Li添加量提高到3~4wt.%左右时,Mgx(Gd,Y,Li)y化合物数量增加且同时逐渐有β相析出。添加Li导致Mg-8Gd-2Y-0.6Zr挤压态合金伸长率明显降低,但可显著降低挤压温度;添加Li 1.5wt.%时,可提高挤压材强度且强化效果随挤压温度降低而显著提高,350℃挤压时的抗拉强度最大,为362.5 MPa,而屈服强度和伸长率最小,分别为235 MPa和5.3%;Li添加量增加至3~4wt.%时,伸长率未显著提高但合金严重软化,不过可实现200℃温挤压。

Mg-8Gd-2Y-0.6Zr alloys with different contents of Li were melt, solidified and extruded. The effects of Li content on microstructures and mechanical properties were investigated. The XRD results indi- cate when Li contents are around 1.5 wt. %, solid solution of α-Mg or Mgx （ Gd, Y, Li） y precipitate forms. When Li contents increase to around 3 - 4 wt. %, quantities of Mgx （ Gd, Y, Li） y compound increase and 13 phase gradually precipitated at the same time with increase of Li. Elongation of Mg-8Gd-2Y-0.6Zr extrusion alloy obviously decreases while extrusion temperature decreases by adding Li. Extrusion bars are strength- ened and strengthening effect obviously increases with the decrease of extrusion temperature by adding 1.5 wt. % of Li. When extrusion temperature is 350 ℃, tensile strength can reach maximum value of 362. 5 MPa,but yield strength and elongation reach maximum values,which are 235 MPa and 5.3% respectively. When Li contents increase to 3 ~ 4 wt. %, elongation not obviously increases and alloys severely softened, but alloys can be extruded at 200 ℃.