Effect of multi-stage solution on microstructure and properties of Al-10.5Zn-2.05Mg-1.02Cu-0.2Zr-0.923Ti alloy extrusion

The effect of multi-stage solution on microstructure and properties was studied in Al-10.5Zn-2.05Mg-1.02Cu-0.2Zr-0.923Ti alloy extrusion. The microstructure, corrosion resistance, plasticity, hardness, and tensile properties of alloy were evaluated using metallographic microscope, X-ray diffraction analysis, micro-hardness tester, and microcomputer-controlled universal testing machine. The results show that the tensile strength and corrosion resistance of the alloy improve first and then deteriorate with increase of solution temperature and holding time, and 2# sample has the best mechanical properties (tensile strength is 711.159 MPa and elongation is 13%) and highest corrosion resistance of alloys. Furthermore, 2# sample has more uniform grains, more equiaxed crystals, and the low-angle grain boundaries, and the dislocation density and the dislocation strengthening contribution of alloy are relatively high. However, the grain grows and the dislocations were consumed with the increase of solution time and temperature, resulting in a decrease in dislocation density and dislocation strengthening contribution. It is indicated that alloy can achieve better comprehensive properties under solution treatment process (450 degrees Cx2 h+460 degrees Cx2 h+470 degrees Cx2 h+480 degrees Cx2 h).