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Abstract：
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 × 1015 m-2), 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.
摘要：
纳米晶(NC)结构可导致金属和合金的显著强化。获得合适的综合力学性能始终是金属材料的目标。这里,纳米结构的Al-Zn-Mg-Cu-Zr-Sc合金成功地通过高压扭转（HPT）和自然时效处理。分析了自然时效HPT合金的显微组织和力学性能。结果表明，自然时效的HPT合金主要由纳米级晶粒(~98.8nm)组成，纳米尺寸的沉淀物（尺寸为20-28nm），和位错（1.16×1015m-2），并表现出851±6MPa的高拉伸强度和6.8±0.2％的适当伸长率。此外,根据晶粒细化强化评估了被激活并有助于合金屈服强度的多种强化模式，降水加强，和位错强化，结果表明，晶粒细化强化和析出强化是主要的强化机制。本研究结果为实现材料的最佳强度-延展性匹配和指导后续退火处理提供了有效途径。
