Effects of Solution Treatment on the Microstructure and Mechanical Properties of Al-Li-Cu-Mg-Ag-Zr Alloy

The effects of solution treatment on the microstructure and mechanical properties of Al-Li-Cu-Mg-Ag-Zr alloy were investigated by means of tensile test,conductivity test,differencial scanning calorimeter(DSC),energy dispersive X-ray(EDX),optical microscopy(OM),scanning electron microscopy(SEM) and transmission electron microscopy(TEM),respectively.The results show that the tensile strength and hardness increase first and then decrease with the increase of the solution temperature when the solution holding time is 30 minutes.The optimal mechanical properties of the alloy are reached at 520 ℃.When the alloy is treated at 520 ℃ for different time,the mechanical properties increase first and then decrease with the increase of solution holding time.The alloy obtains the optimum pattern of microstructure with a large quantity of dispersive fine T1 phase and best mechanical properties when it is treated at 520 ℃ for 30 minutes.The fracture mechanism of the alloy is mixed fracture consisting of transgranular fracture and intergranular layered cracks.The alloy gets overburnt when the solution temperature is 525 ℃.