中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 32 No. 5 May 2022 |
（1. School of Metallurgy and Materials, University of Birmingham, B15 2TT, United Kingdom;
2. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
3. Key Laboratory of Nonferrous Metallic Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China;
4. Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China）
Abstract:An ultrafine-grained Al-Zn-Mg-Zr alloy with superior mechanical performance was obtained by high passes of equal angular pressing (ECAP) and subsequent aging. After 8 ECAP passes and aging, the yield strength (YS) and ultimate tensile strength (UTS) of the solid-solutioned alloy are significantly improved from (98±10) and (226±7) MPa to (405±9) and (427±9) MPa, respectively. A large elongation is also maintained ((17.4±2.5)%). The microstructure features including grain refinement, morphology of precipitates, and dislocation density, were revealed with multiscale characterizations, including transmission electron microscopy, electron backscattered diffraction, and X-ray diffraction. After 8 passes of ECAP, the original coarse elongated grains are refined to a unique bimodal grain structure consisting of ultrafine equiaxed and lath-like grains. Additionally, the effects of ECAP and subsequent aging on the strengthening contribution of a variety of strengthening mechanisms, such as dislocation strengthening and precipitation strengthening, were discussed in detail.
Key words: equal angular pressing; Al-Zn-Mg-Zr alloy; grain refinement; strengthening mechanism
