摘要
采用x射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、力学性能测试、剥落腐蚀、晶间腐蚀、和电化学工作站等实验手段,研究了不同Mg/Si(原子分数比,下同)对Al-Mg-Si铸造合金的力学性能、腐蚀性能及微观组织的影响。研究表明,Mg/Si为1.1时合金具有最佳的力学性能和耐蚀性(抗拉强度和屈服强度分别为275和253MPa,晶间腐蚀深度为73.76μm);Mg/Si在1.1~3.1之间,强度随Mg/Si升高而下降,Mg/Si增大到3.1时,抗拉强度仅为181MPa,延伸率随Mg/Si升高而增加,但变化幅度不大;晶间腐蚀敏感度大体上随Mg/Si减小而升高,但在Mg/Si为1.1时耐晶间腐蚀性能有显著的提高;剥落腐蚀敏感度无太大差异,均为PA等级,耐剥落腐蚀性能良好。T6热处理态晶内析出相析出密度随Mg/Si增加发生变化,低Mg/Si的合金1的析出密度高于高Mg/Si的合金3,高分辨结果显示晶内析出相为强化相,并且在晶界处均未观察到明显析出相和无沉淀析出带(PFZ)。
The effect of different Mg/Si ratio on themicrostructureand properties of Al-Mg-Si casting alloy was investigated through X- ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), mechanical properties tes- ting, exfoliation corrosion, intergranular corrosion, and electrochemical workstation. The studies showed that the alloy had the optimal mechanical properties and corrosion resistance when Mg/Si ratio was 1.1 ( the tensile strength and yield strength of the alloy were 275 and 253 MPa, respectively, and the corrosion depth was 73.76 μm). When Mg/Si ratio ranged from 1. 1 to 3.1, the strength decreased with increasing Mg/Si ratio, when Mg/Si ratio increased to 3.1, the tensile strength was 181 MPa, and the elongation increased at a low rate with increasing Mg/Si ratio. In general, the intergranular corrosion sensitivity increased with the decrease of the Mg/Si ratio, but the intergranular corrosion resistance of the alloys could be improved significantly when the Mg/Si ratio was 1. 1. However, the exfoliation corrosion sensitivity showed no remarkable difference, and the corrosion degree of the alloys was both PA with excellent exfoliation corrosion resistance. Under the condition of T6, the density of the precipitated phase of the alloys changed with increasing Mg/Si ratio. It was shown that the precipitation density of Alloy 1 with lower Mg/Si was higher than that of higher Mg/Si ratio (Alloy 3 ) , and the precipitated phase was strengthening phase β″ by the HRTEM results. Additionally, no significant precipitation or precipitation free zone (PFZ) was observed at the grain boundary for the different alloys.
作者
汪娟
罗兵辉
柏振海
高阳
郑亚亚
任智炜
Wang Juan;Luo Binghui;Bai Zhenhai;Gao Yang;Zheng Yaya;Ren Zhiwei(School of Materials Science and Engineering, Central South University, Changsha 410083, China)
出处
《稀有金属》
EI
CAS
CSCD
北大核心
2018年第7期681-690,共10页
Chinese Journal of Rare Metals
基金
中国国防科技工业局项目(2011-006)资助