中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 15 No. 6 December 2005 |
（1. Institute of Microstructure and Property of Advanced Materials,
Beijing University of Technology, Beijing 100022, China;
2. School of Materials Science and Engineering, Central South University,
Changsha 410083, China）
Abstract: The effects of different contents of rare earth element, and erbium, on the as-cast microstructures of Al-6Zn-2Mg and Al-6Zn-2Mg-1.8Cu alloys were studied by optical microscopy, scanning electron microscopy, X-ray diffractometry, transmission electron microscopy and EDS analysis. The results show that the netlike structure of as-cast alloys can be remarkably refined, and the distance of dendritic structure decreases, with Er addition. However, the improvement results on Al-Zn-Mg-Cu are not better than that of Al-Zn-Mg. Er and Al can interact to form Al3Er phase, which is coherent with α(Al) matrix, with trace Er addition to the Al-Zn-Mg alloy. The refinement effect of Al-Zn-Mg alloys is familiar with the formation and precipitation of coherent Al3Er phases. The ternary compound AlCuEr, similar with AlCuSc phase, will form when Er is added to Al-Zn-Mg-Cu alloy, which suppresses the formation of Al3Er phase and doesn’t solve in the following heat treatment.
Key words: Al-Zn-Mg alloy; Al-Zn-Mg-Cu alloy; rare earth; Er; microstructure; aluminum alloy; refinement
