Significant Enhancement in Tensile Strength of Room-Temperature Rolled Al-8zn-1mg Alloy Induced by Profuse Microbands

Developing high-performance simpler alloys via simpler processing procedures is of great significance in achieving carbon dioxide emission peak and carbon neutrality. In the present study, room-temperature (RT) rolling was carried out on simple ternary Al–8Zn–1Mg alloy in order to improve its comprehensive performance by regulating microstructure evolution. Ultimate tensile strength (UTS), yield strength (YS), fracture elongation (EL%) and uniform elongation (EU%) were tested. Optical microscopy (OM), electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) were used to characterize the microstructure evolution. Phase analysis was performed by X-ray diffraction (XRD). The results show that RT rolling significantly enhances the UTS and YS of ternary Al–8Zn–1Mg alloy, which are ∼447 MPa and ∼389 MPa, respectively, with the corresponding EL% and EU% of ∼7.1% and ∼4.1%. The comprehensive tensile properties are comparable to or even better than that of their conventional counterparts with more complex compositions or produced by more complicated techniques. Compared with the as-SS alloy, the as-SS + R alloy experiences an additional 227 MPa increase in YS. The calculated results show that fine-grain strengthening and dislocation strengthening (predominantly in the form of microbands in the present study) respectively contribute to 21 MPa and 167 MPa increases in YS. The remaining 40 MPa increase is highly likely derived from the hetero-deformation induced (HDI) strengthening of the heterostructured lamellar microbands. The delicate balance between strength and elongation is mainly attributed to the profuse microbands formed by the coupling effect of high Zn solute atoms and stress. The findings shed light on a fundamental facet of how regulating microbands can develop high performance simpler aluminum alloys which have potential applications in strength-based structural materials.