Mg-Zn-Sn铸造合金的组织及力学性能

Microstructure and Mechanical Properties of Mg-Zn-Sn Casting Alloys

通过改变Zn、Sn含量,采用金属型铸造了Mg-Zn-Sn合金,研究了其铸态组织及力学性能。结果表明,在Zn、Sn总含量≤6%时,随着元素含量增加,Mg-Zn-Sn合金的组织由柱状晶向等轴晶转变,且等轴晶晶粒尺寸和二次枝晶间距减小,原因是生长限制因子G_(RF)值随着元素含量增加而增大;而第二相MgZn及(或)Mg_(2)Sn数量则随元素含量增加而增加;屈服强度及压缩强度随Zn、Sn含量增加而增大,压缩率在Zn、Sn含量均为2%时达到最高,这是由于Mg_(2)Sn及MgZn相变得细小且均匀分布在晶界,提高了合金的塑性。

Mg-Zn-Sn alloys with different contents of Zn and Sn were prepared by metal mold,and the as-cast structure and mechanical properties of the alloys were investigated.The results show that the morphology of the grains is changed from columnar to equiaxed and the equiaxed grain size as well as the secondary dendrite spacing is decreased as the element content increases when the total mass fraction of Zn and Sn is less than or equal to 6%due to the value of G_(RF)(Growth restriction factor)increases.However the amount of second-phase MgZn and/or Mg_(2)Sn is increased with Zn and Sn content increasing.The yield strength and compressive strength of the alloy are increased with the content of Zn and Sn increasing,however the compressive rate of the alloys reaches the highest values at 2%Zn and 2%Sn,which is attributed to the finer and uniform distribution of Mg_(2)Sn and MgZn phases at the grain boundaries,thus improving the plasticity.