Investigation of Microstructures and Mechanical Properties of Ultra-High Strength Al-Zn-Mg-Cu Alloy Prepared by Rapid Solidification and Hot Extrusion

Al-Zn-Mg-Cu aluminum alloys have the advantages of high specific strength, easy processing, and toughness, showing great potential application in aerospace field. However, ultra-high strength usually contain coarse microstructures, micro-segregation, casting defects that seriously deteriorate mechanical properties. Here, we report a high-strength alloy (Al-10.5Zn-2.0Mg-1.2Cu-0.12Zr-0.1Er) prepared by rapid solidification hot extrusion to explore microstructure modification based on this strategy. The results show that: rapid-solidification technology can significantly refine grains, ribbons were composed α (Al) equiaxed fine average grain size was less than 6 μm. After extrusion, had partially recrystallized, existing second-phase (T-phase) needle-shaped precipitates MgZn2 (η-phase), tensile elongation extruded bar 466.4 MPa 12.9%, respectively. T6 heat treatment, reached 635.8 MPa, while decreased 10.5%. According analysis considering contributions boundary, dislocation, precipitation-strengthening improvement properties, it found is main strengthening mechanism. Our research shows hot-extrusion for improving microstructures properties alloys.