Effect of solution treatment and artificial aging on microstructure and mechanical properties of Al-Cu alloy

In order to achieve good mechanical properties of Al-Cu alloys such as high strength and good toughness, precipitation hardening and artificial aging treatment were applied. As defined by the T6 heat treatment, the standard artificial aging treatment for Al-Cu alloy followed heat treatments of solution treatment at 510-530 degrees C for 2 h, quenching in water at 60 degrees C and then artificial aging at 160-190 degrees C for 2-8 h. The effects of solution treatment and artificial aging on the microstructure and mechanical properties of Al-Cu alloy were studied by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and tensile test. The results of solution treatment indicate that the mechanical properties of Al-Cu alloy increase and then decrease with the increase of solution temperature. This is because the residual phases dissolve gradually into the matrix, and the fraction of the precipitation and the size of the re-crystallized grain increased. Compared to the solution temperature, the solution holding time has less effect on the microstructure and the mechanical properties of Al-Cu alloy. The artificial aging treatments were conducted at 160-180 degrees C for 2-8 h. The results show that the ultimate tensile strength can be obtained at 180 degrees C for 8 h. Ultimate tensile strength increased with increasing time or temperature. Yield strength was found as the same as the ultimate tensile strength result.