中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 24 No. 12 December 2014 |
（1. College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China;
2. Institute of Multipurpose Utilization of Mineral Resources,
Chinese Academy of Geological Sciences, Chengdu 610041, China）
Abstract:The Al-9Zn-2.8Mg-2.5Cu-xZr-ySc alloys (x=0, 0.15%, 0.15%; y=0, 0.05%, 0.15%), produced by low-frequent electromagnetic casting technology, were subjected to homogenization treatment, hot extrusion, solution and aging treatment. The effects of minor Sc and Zr addition on microstructure, recrystallization and properties of alloys were studied by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that Sc and Zr addition can refine grains of the as-cast alloy by precipitation of primary Al3(Sc,Zr) particles formed during solidification as heterogeneous nuclei. Secondary Al3(Sc,Zr) precipitates formed during homogenization treatment strongly pin the movement of dislocation and subgrain boundaries, which can effectively inhibit the alloys recrystallization. Compared with the alloy without Sc and Zr addition, the Al-Zn-Mg-Cu-Zr alloy with 0.05% Sc and 0.15% Zr shows the increase in tensile strength and yield strength by 172 MPa and 218 MPa, respectively. Strengthening comes from the contributions of precipitation, substructure and grain refining.
Key words: aluminum alloy; low-frequent electromagnetic casting; inhibit recrystallization; primary Al3(Sc,Zr) particles; secondary Al3(Sc,Zr) particles; substructure strengthening; precipitation strengthening; grain refining
