Effects of Cd and Sn on double-peak age-hardening behaviors of Al-Si-Cu-Mg cast alloys  

作　　者：Li Runxia Chen Yujin Yuan Xiaoguang Qu Yingdong Li Rongde 

机构地区：[1]Institute of Material Science and Engineering, Shenyang Universi~ of Technology, Shenyang 110178, China

出　　处：《China Foundry》2010年第1期1-5,共5页中国铸造（英文版）

摘　　要：The effects of trace elements Cd and Sn on precipitation process of Al-Si-Cu-Mg cast alloys were investigated in the present research.It is shown that the addition of Cd and Sn not only increases remarkably the aging peak hardness and reduces the time to reach aging peak,but also eliminates the double-aging-peak phenomenon which appears in Al-Si-Cu-Mg alloys.In Al-Si-Cu-Mg alloys the first aging peak corresponds to GP zones(especially GPⅡ) ,and the second one is caused by metastable phases.The obvious time interval of transition from GPⅡ to metastable phases associates with the double-aging-peak phenomenon.The results of DSC and TEM show that Cd/Sn elements suppress the formation of GPⅠzone,stimulate the formation of θ",θ' and θ phases,and then shorten remarkably the temperature intervals of each exothermic peak.Because the transition interval between GPⅡzone and metastable phases is shortened by Cd/Sn in Al-Si-Cu-Mg cast alloys,θ' phase coexists with θ" phase in matrix of ageing peak condition,which causes effective hardening on the alloys,and at the same time,eliminates the double-aging-peak phenomenon.The effects of trace elements Cd and Sn on precipitation process of Al-Si-Cu-Mg cast alloys were investigated in the present research. It is shown that the addition of Cd and Sn not only increases remarkably the aging peak hardness and reduces the time to reach aging peak, but also eliminates the double-aging-peak phenomenon which appears in Al-Si-Cu-Mg alloys. In Al-Si-Cu-Mg alloys the first aging peak corresponds to GP zones （especially GP Ⅱ）, and the second one is caused by metastable phases. The obvious time interval of transition from GP Ⅱ to metastable phases associates with the double-aging-peak phenomenon. The results of DSC and TEM show that Cd/Sn elements suppress the formation of GP Ⅰzone, stimulate the formation of θ＂, θ＇ and θ phases, and then shorten remarkably the temperature intervals of each exothermic peak. Because the transition interval between GP Ⅱ zone and metastable phases is shortened by Cd/Sn in Al-Si-Cu-Mg cast alloys, θ＇ phase coexists with θ phase in matrix of ageing peak condition, which causes effective hardening on the alloys, and at the same time, eliminates the double-aging-peak phenomenon.

关 键 词：Al-Si-Cu-Mg cast alloys Cd/Sn addition AGE-HARDENING precipitation 

分 类 号：TG146[一般工业技术—材料科学与工程] TG146.21[金属学及工艺—金属材料]