Investigation on microstructure and properties of a new type Al-Zn-Mg-Cu alloy profile after duplex aging treatment

In this paper,the tensile properties,electrical conductivity and microstructure of a new type Al-Zn-Mg-Cu alloy profile after aging for 4h at 120℃ plus 8h at 165℃ were tested by tensile testing,optical microscopy(OM),scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results show that the ultimate tensile strength,yield strength,elongation and electrical conductivity are 548MPa,514.5MPa,11.6% and 41.7%IACS,respectively.Compared to 7050 alloy profile of T73 temper,the ultimate tensile strength,yield strength and elongation of the alloy increase by 4.7%,11.6%,and 12.6%,while the electrical conductivity is equivalent.The fracture mode of the alloy is transgranular shearing fracture,and the major precipitates in the alloy are η′and η phases under the aging condition.The alloy profile can obtain good strength and suitable toughness.