混合稀土(La,Ce)对7A04铝合金组织与性能的影响

Effect of Mixed Rare Earth(La,Ce)on Microstructure and Properties of 7A04 Aluminum Alloy

采用铸造的方法制备了La/Ce配比不同及含量不同的7A04铝合金,通过光学显微镜、扫描电镜、X射线衍射分析、显微硬度和耐腐蚀性能测试等手段,研究了混合稀土(La,Ce)配比不同及含量不同对7A04铝合金组织和性能的影响。结果表明,添加一定量的混合稀土后,7A04铝合金主要由α⁃Al基体、MgZn_(2)和Al_(2)Cu第二相、Al_(8)Cu_(4)(LaCe)和Al_(3)(LaCe)稀土相所组成,其中稀土相主要呈块状和骨骼状分布于晶界处,有效抑制了晶粒的生长,铝合金晶粒得到明显细化;铝合金的显微硬度和耐腐蚀性能均随稀土含量的增加呈先增大后减小的变化趋势,在La/Ce配比为7∶3、含量为0.8%时铝合金的硬度值最大为225 HV0.3,相对未添加稀土的铝合金硬度提高了31%;在La/Ce配比为5∶5、含量为0.5%时铝合金的腐蚀速率和腐蚀电流密度值最低,容抗弧半径最大,其耐腐性能最好。

In this paper,7A04 aluminum alloys with different mixed rare earth(La,Ce)ratios and contents are pre⁃pared by casting method.The microstructure and properties of the 7A04 aluminum alloys are studied by means of optical micro⁃scope,scanning electron microscope,X⁃ray diffraction analysis,microhardness and corrosion resistance test.The results show that after adding a certain amount of mixed rare earths,7A04 aluminum alloy is mainly composed ofα⁃Al matrix,MgZn_(2)and Al 2Cu second phase,Al_(8)Cu_(4)(LaCe)and Al_(3)(LaCe)rare earth phases.The rare earth phase is mainly distributed at the grain boundary in the shape of block and bone,which effectively inhibits the growth of aluminum alloy grains,and the grain refine⁃ment is obvious.The microhardness and corrosion resistance of aluminum alloy increase firstly and then decrease with the in⁃crease of rare earth content.When the ratio of rare earths is 7∶3 and the rare earth content is 0.8%,the maximum hardness of aluminum alloy is 225 HV0.3,which is 31%higher than that of aluminum alloy without rare earth.When the ratio of rare earths is 5∶5 and the content of rare earth is 0.5%,the corrosion rate and current density of aluminum alloy are the lowest,and the arc radius of capacitance is the largest,and the corrosion resistance is the best.