La和Er对Al-13Si-5Cu-2Ni-1Mg合金组织和性能的影响

研究了La和Er对铸造Al-13Si-5Cu-2Ni-1Mg合金组织和力学性能的影响。结果表明,La对共晶Si有较强的变质作用,在合金中生成块状、长针状富La相;Er可以明显减小二次枝晶间距,在合金中可生成块状、短棒状富Er相。合金中复合添加0.2%的La和0.2%的Er时,二次枝晶间距、初生Si、共晶Si和金属间化合物的尺寸同时减小,La、Er相互作用可以抑制富稀土相的生长,使合金中引入尺寸细小且弥散分布的富稀土相,此时合金力学性能最佳,25和350℃时抗拉强度分别为274MPa和91MPa。

Effects of La and Er on Microstructure and Properties of Al-13Si-5Cu-2Ni-1Mg Alloy

The effects of La and Er on the microstructure and mechanical properties of cast Al-13Si-5Cu-2Ni-1Mg alloy were investigated by OM,SEM,EOS and tensile testing.The results reveal that La has a stronger modification effect on eutectic silicon,forming bulk and long needle-like La-rich phases in the alloy,and Er can reduce significantly the secondary dendrite spacing,and massive,short rod-like Er-rich phases can be generated in the alloy.With 0.2% La and 0.2% Er compound addition,the secondary dendrite spacing,primary silicon,eutectic silicon and intermetallic compound can be refined at the same time.The interaction of La and Er can inhibit the growth of RE-rich phase,and the RE-rich phase with a small size and a dispersed distribution can be introduced into the alloy,so the tensile performance presents desirable,where the tensile strength of the alloy can reach 274 MPa and 91 MPa at 25℃ and 350℃,respectively.