Effects of Extrusion and Heat Treatment Conditions on Microstructure and Mechanical Properties of an Al-Zn-Mg-Cu-Er Alloy

In this study, the effect of Al-30Er grain refiners, extrusion and heat treatment conditions on an Al-15Zn-2.5 Mg-2.5Cu alloy was studied. The optimum level of Er was found to be 1 wt%. Microstructural examinations and fracture surfaces were conducted by scanning electron microscopy coupled with an energy dispersive spectrometry. T6 heat treatment including quenching to room temperature and aging at 120 degrees C for 24 h was employed to reach to the maximum strength. Significant improvements in mechanical properties were obtained with the addition of grain refiner combined with T6 heat treatment and extrusion process. The average ultimate tensile strength (UTS) of the specimens before and after T6 heat treatment and extrusion processes increases from 225 to 602 MPa. Adding of 1 wt% Er, T6 heat treatment and extrusion process make about 167% enhancement in tensile strength compared to that of unreinforced aluminum alloy.