Characterizations of precipitation behavior of Al-Mg-Si alloys under different heat treatments

作     者：Hui Li Jia-yi Wang Hai-tao Jiang Zheng-feng Lu Zhen-feng Zhu 

作者机构：College of EngineeringYantai Nanshan UniversityYantai 265700China Institute of Engineering TechnologyUniversity of Science and Technology BeijingBeijing 100083China National Engineering Research Center for Plastic Working of Alulinum AlloysShandong Nanshan Aluminum Co.Ltd.Yantai 265713China 

出 版 物：《China Foundry》 (中国铸造（英文版）)

年 卷 期：2018年第15卷第2期

页      面：89-96页

核心收录：

学科分类：0806[工学-冶金工程] 08[工学] 0805[工学-材料科学与工程（可授工学、理学学位）] 080502[工学-材料学] 0703[理学-化学] 0702[理学-物理学] 

基　　金：financially supported by the Natural Science Foundation of Shandong Province(ZR2016EMQ11) the Major Research and Development Program of Shandong Province(2017GGX20119),China 

主　　题：Al-Mg-Si alloy heat treatment precipitation behavior electrical resistivity 

摘      要：The solidification-precipitation behavior of Al-Mg-Si multicomponent alloys has long been an absorbing topic. Experiments were carried out to analyze the precipitation behaviors of Al-Mg-Si alloys under different heat treatments. All specimens were homogenized at 570 ℃ for 8 h, and then solution treated at 540 ℃ for 55 min. Subsequently, the specimens were age treated for different times at temperatures of 100 ℃, 150 ℃ and 180 ℃, respectively. The experimental results show that the occurrence of dispersed free zones （DFZ） is caused by the uneven distribution of dispersed phase. During the aging process, pre-β＂ phases form at the initial stage and an aging temperature of 100 ℃is too low to complete the transformation of pre-β＂ to β＂. At 150℃, the precipitation sequence is concluded as SSSS-pre-β＂-pre-β＂＋β＂-β＂-β＇-β. Moreover, changes in sizes and densities of the pre-β＂, β＂and β＇ phases during the aging process has an important influence on the evolution of microhardness and electrical resistivity. The microhardness peak value of 150 ℃ is similar to that of 180 ℃, which is -141 HV. While, at 100℃, the microhardness increases slowly, and the attainable value is 127 HV up to 19 days. When the aging temperature is 100 ℃, the electrical resistivity has the highest average value. When the aging temperature exceeds 100 ℃, with the occurrence and growth of β＂and β＇, the resistivity has a distinct decrease with prolonged aging time.