Effects of Ag Addition on Precipitation and Fatigue Crack Propagation Behavior of a Medium-Strength Al–Zn–Mg Alloy

作     者：Lianghua Lin Zhiyi Liu Wenjuan Liu Yaru Zhou Tiantian Huang 

作者机构：School of Material Science and Engineering Central South University Key Laboratory of Nonferrous Metal Materials Science and Engineering Ministry of Education Central South University 

出 版 物：《Journal of Materials Science & Technology》 (材料科学技术（英文版）)

年 卷 期：2018年第34卷第3期

页      面：534-540页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：financially supported by the National Key Research and Development Program of China (No. 2016YFB0300900) the National Natural Science Foundation of China (No. 51171209) 

主　　题：Aluminum alloy Fatigue crack propagation Precipitate free zones Silver 

摘      要：Effects of trace addition of Ag on the fatigue crack propagation behavior and microstructure of a mediumstrength aged AI-Zn-Mg alloy were investigated in the present work. The results show that a combination of enhanced tensile strength and improved fatigue crack propagation resistance in Al-Zn-Mg alloys is achieved with small addition of Ag. The enhanced strength is attributed to the high density of η＇ precip- itates within the grains and narrow precipitate free zones in the vicinity of grain boundaries. The main contribution to the improvement of fatigue crack propagation resistance comes from the coarser precipitates within the grains. When subjected to two-step aging. Ag-added alloy shows larger semi-coherent matrix precipitates. These relatively coarser precipitates increase the homogeneity of deformation and therefore improve the fatigue crack propagation resistance. In addition, microstructure analysis indicates that the size and distribution of inclusions as well as the grain structures of Al-Zn-Mg alloys are independent of Ag addition.