Cu含量对铝锂合金组织、力学性能和腐蚀行为的影响

Effect of Cu content on microstructure,mechanical properties and corrosion behavior of Al-Li alloy

采用扫描电镜(SEM)、透射电镜(TEM)、万能试验机和电化学工作站等研究了T6时效处理Al-xCu-1.0Li-0.5Mg-0.4Zn-0.4Mn(x=2.0、3.2、3.4、3.6、4.0)合金板材的微观组织、力学性能及耐腐蚀性能。结果表明,Cu含量的增加促进合金的强度提升。当Cu含量为3.4%时,合金表现出优异的综合力学性能,其抗拉强度为360.4 MPa,伸长率为17.1%。铝铜锂合金的断裂形式在Cu含量为2.0%和3.4%时表现为韧性断裂、在Cu含量为3.2%时表现为混合断裂、在Cu含量为3.6%和4.0%时表现为脆性断裂。当Cu含量为3.2%时,合金表现出良好的耐腐蚀性能。Cu含量的增加有助于T_(1)相和立方相的析出,从而提高合金的力学性能,但过多的立方相会降低耐蚀性。

Microstructure,mechanical properties and corrosion properties of Al-xCu-1.0Li-0.5Mg-0.4Zn-0.4Mn(x=2.0,3.2,3.4,3.6,4.0)alloy plates treated by T6 aging were investigated by means of scanning electron microscope(SEM),transmission electron microscope(TEM),mechanical testing machine and electrochemical workstation.The results show that the strength of the alloy increases with the increase of Cu content.When the Cu content is 3.4%,the alloy has optimal properties with tensile strength of 360.4 MPa and elongation of 17.1%.The fracture modes of aluminum-copper-lithium alloy exhibit ductile fracture at Cu content of 2.0% and 3.4%,mixed fracture at Cu content of 3.2%,and brittle fracture at Cu content of 3.6% and 4.0%.The alloy exhibits optimal corrosion resistance when the Cu content is 3.2%.With the increase of Cu content,it is beneficial to precipitate of T_(1) phase and cubic phase,which leads to improve the mechanical properties of the alloy,while excessive cubic phase may reduce the corrosion resistance.