Y对铸态Al-2.5%Cu合金组织和性能影响的研究

Effect of Addition of Yttrium on As-cast Microstructure and Properties of Al-2.5%Cu Alloy

采用扫描电镜、X射线衍射仪、拉伸试验机、涡流导电率仪等实验手段,研究质量分数为0-0.25%的Y对Al-2.5%Cu合金铸态组织和性能的影响。结果表明,Y加入Al-2.5%Cu合金中主要形成Al6Cu6Y与Al3Y相弥散分布在晶界上,且Y可以显著细化α-Al枝晶并减小二次枝晶间距,但随着Y含量的增加,导电率呈平缓下降趋势;Y加入量小于0.20%时,随含量增加细晶作用明显;当Y含量为0.20%时,铸态合金组织中晶粒细化效果最为显著,晶粒尺寸减小至30μm左右,第二相出现球化现象,力学及耐热性能达到峰值;当Y加入达到0.25%时,晶粒粗化,力学及耐热性能下降。

The effects of addition of 0 ~ 0. 25% yttrium on as- cast microstructure and properties of Al-2. 5% Cu alloy were investigated by using scanning electron microscope,X- ray diffraction,tensile testing machine and eddy conductivity meter,etc. Results reveal that the Al6Cu6 Y and Al3 Y phase resulting from addition of yttrium to the Al-2. 5% Cu alloy was distributed at the grain boundary,the addition of rare earth yttrium can refine the α-Al dendrites and reduce the secondary dendritic arm spacings,but the conductivity reduce significantly with the increase of yttrium addition; The as- cast microstructure of Al-2. 5% Cu alloy was gradually fined when quantity of yttrium was under 0. 20%; The grain size reduced to 30μm was fined remarkably with addition of 0. 20% yttrium,and the second phases of the Al- 2. 5% Cu alloy were sphericized,mechanical and thermal properties can be improved; However the as- cast microstructure of the alloy was observed gradually becoming coarse when the percentage of the yttrium increased to 0. 25%,which leads to the reduction of mechanical and thermal properties.