不同峰时效处理后Al-Cu-Mg-Ag合金的显微组织和晶间腐蚀性能

通过维氏硬度试验、拉伸试验、晶间腐蚀试验、极化曲线试验以及透射电镜和扫描电镜观察,研究了不同峰时效状态(165 ℃/16 h、180 ℃/6 h和190 ℃/2 h)下Al-Cu-Mg-Ag合金的力学性能、显微组织和晶间腐蚀性能的差异。研究结果表明: 3种峰时效状态下,180 ℃/6 h时效状态合金的Ω相和θ'相总数量密度最高,其抗拉强度和屈服强度分别为513.6 MPa和463.4 MPa。当时效温度达到190 ℃时,θ'相迅速粗化从而抑制Ω相的析出,降低了Ω相的数量密度。另外,不同峰时效状态的无沉淀析出带(PFZ)宽度从大到小依次为: 180 ℃/6 h>190 ℃/2 h>165 ℃/16 h。由于在晶间腐蚀过程中,PFZ作为阳极优先被腐蚀,因此180 ℃/6 h时效状态合金的抗晶间腐蚀性能最差,而165 ℃/16 h时效状态合金的抗晶间腐蚀性能最好。

Microstructure and Intergranular Corrosion of Al-Cu-Mg-Ag Alloy After Different Peak Aging Condition

The differences in the mechanical properties, microstructure and intergranular corrosion of an Al-Cu-Mg-Ag alloy in different peak aging condition (165 ℃/16 h, 180 ℃/6 h and 190 ℃/2 h) were investigated by means of Vickers hardness test, tensile test, intergranular corrosion test, polarization curve test, transmission electron microscope and scanning electron microscope observation. The results show that under three different conditions, the alloy with the peak aging condition of 180 ℃/6 h has the highest value in the total number density of Ω phase and θ' phase, and also has the tensile strength and yield strength respectively at 513.6 MPa and 463.4 MPa. With an aging temperature of 190 ℃,the rapid coarsening of the θ' phase suppresses the precipitation of the Ω phase, leading to a decrease in the number density of the Ω phase. In addition, the width of precipitation free zones (PFZ) in different peak aging condition can be ranked in the following order: 180 ℃/6 h>190 ℃/2 h>165 ℃/16 h. During the intergranular corrosion, the PFZ, as the anode, is preferentially corroded. Therefore, the alloy with aging condition of 180 ℃/6 h has the worst intergranular corrosion resistance, while alloy with aging condition of 165 ℃/16 h has the best intergranular corrosion resistance.