Microstructures and Mechanical Properties of a Nanostructured Al-Zn-Mg-Cu-Zr-Sc Alloy under Natural Aging

• Published in: Materials Vol. 16; no. 12; p. 4346
• Main Authors: Shen, Gaoliang, Xiang, Zhilei, Ma, Xiaozhao, Huang, Jingcun, Li, Jihao, Wang, Bing, Zhou, Zongyi, Chen, Yilan, Chen, Ziyong
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 13.06.2023; MDPI
• Subjects: Aging (natural); Al-Zn-Mg-Cu-Zr-Sc alloy; Alloys; Aluminum; Analysis; Annealing; Copper; Copper base alloys; Ductility; Elongation; Grain boundaries; Grain refinement; Grain size; high-pressure torsion; Magnesium; Mechanical properties; Microscopy; Microstructure; Nanostructure; natural aging; Precipitates; Precipitation hardening; Scandium; Shear strain; Specialty metals industry; Strengthening; Tensile strength; Zinc; Zinc compounds; Zirconium; China; United States > US; Al-Zn-Mg-Cu-Zr-Sc alloy; natural aging; microstructure; high-pressure torsion; mechanical properties
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma16124346

Nanocrystalline (NC) structure can lead to the considerable strengthening of metals and alloys. Obtaining appropriate comprehensive mechanical properties is always the goal of metallic materials. Here, a nanostructured Al-Zn-Mg-Cu-Zr-Sc alloy was successfully processed by high-pressure torsion (HPT) followed by natural aging. The microstructures and mechanical properties of the naturally aged HPT alloy were analyzed. The results show that the naturally aged HPT alloy primarily consists of nanoscale grains (~98.8 nm), nano-sized precipitates (20-28 nm in size), and dislocations (1.16 × 10 m ), and exhibits a high tensile strength of 851 ± 6 MPa and appropriate elongation of 6.8 ± 0.2%. In addition, the multiple strengthening modes that were activated and contributed to the yield strength of the alloy were evaluated according to grain refinement strengthening, precipitation strengthening, and dislocation strengthening, and it is shown that grain refinement strengthening and precipitation strengthening are the main strengthening mechanisms. The results of this study provide an effective pathway for achieving the optimal strength-ductility match of materials and guiding the subsequent annealing treatment.