(1. 中南大学 材料科学与工程学院，长沙410083；
2. 东北轻合金有限责任公司，哈尔滨150060)
摘 要: 采用拉伸和疲劳力学性能测试、金相和透射电子显微分析，研究2524和用微量Sc和Zr合金化的2524SZ合金T3态薄板的组织和性能，考察微量Sc和Zr合金化对2524SZ合金T3态薄板疲劳裂纹扩展特性的影响。结果表明：微量Sc和Zr在2524SZ合金中主要以次生的Al3(Sc, Zr)粒子形式存在，这种粒子与基体共格，固溶处理过程中能部分抑制合金的再结晶，基体晶粒组织主要由细小的亚晶组成；在相近的应力强度因子ΔK条件下，2524和2524SZ合金T3态薄板的疲劳裂纹扩展速率分别为4.50和2.35 μm/ cycle，表明添加微量Sc和Zr能显著降低 2524SZ合金抵抗疲劳裂纹扩展速率；亚晶强化和Al3(Sc, Zr)相析出强化是微量Sc和Zr使2524SZ合金疲劳裂纹扩展速率降低的主要原因。
关键字: 2524SZ合金；Sc；Zr；亚晶；Al3(Sc, Zr)析出相；疲劳裂纹；扩展特性
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Northeast Light Alloy Co. Ltd, Harbin 150060, China）
Abstract:The microstructures and properties of 2524-T3 alloy sheet and 2524SZ-T3 alloy sheet with minor Sc and Zr, were investigated by tensile test, OM and TEM analysis. The effects of minor Sc and Zr on the fatigue crack development characteristics of 2524SZ alloy sheet were studied. The results show that in 2524SZ aluminum alloy, minor Sc and Zr exist as secondary Al3(Sc, Zr) precipitates，which can partly prohibit recrystallization, and the matrix mainly consists of subgrain. At the similar ΔK value, the fatigue crack propagation rates of 2524 and 2524SZ alloy sheets are 4.50 and 2.35 μm/cycle, respectively, showing that minor Sc and Zr can obviously decrease the fatigue crack propagation velocity. Subgrain structure and Al3(Sc, Zr) precipitates are responsible for the decrease of the fatigue crack propagation velocity of 2524SZ alloy.
Key words: 2524SZ alloy; scandium; zirconium; subgrain structure; Al3(Sc, Zr) precipitate; fatigue crack; propagation characteristics
