摘要
通过进行透射电镜分析和拉伸试验研究了不同时效处理制度对Al-7.2Zn-2.5Mg-1.5Cu-0.08Zr-0.12Sc合金的显微组织及拉伸性能的影响。透射电镜分析结果表明:合金在时效过程中,晶内析出大量弥散分布的Mg Zn2相与Al3(Sc,Zr)相。单级时效状态下,晶内析出相细小,晶界析出断续分布的平衡相,并存在晶界无沉淀区;双级时效状态下,晶内及晶界析出相均长大,晶间无析出带宽化;回归再时效处理状态下,晶内析出相较单级时效略有长大,晶界处组织与双级时效相似。拉伸试验结果表明:单级时效状态下的合金具有较高的强度,但断裂伸长率较小;双级时效状态下的合金强度较单级时效明显降低,但有较大的断裂伸长率;经回归再时效的合金既保证了单级时效的强度,也具有双级时效的伸长率。
Effect of aging treatment on microstructure and tensile properties of an extruded Al-7.2Zn-2.5Mg-1.5Cu-0.08Zr-0.12 Sc alloy was investigated by means of transmission electron microscopy and tensile tests.The results show that a large amount of dispersed Mg Zn2 and Al3（Sc,Zr） precipitates appear inside the grains during the aging treatment.The precipitates inside the grains are fine,the discontinuous equilibrium phase is precipitated at the grain boundaries and the precipitate free zones near the grain boundaries are observed for the alloy after the single-stage aging.For the alloy subjected to the double-stage aging treatment,the precipitates inside the grains and at the grain boundaries coarsen,and the precipitate free zone widens.In the retrogression and reaging state,the precipitates inside the grains slightly grow compared with that of the single aging treatment,and the microstructure near the grain boundaries is similar to those in the double-stage aging state.The results of tensile tests show that the strength of the alloy subjected to the single-stage aging treatment is high,but its elongation to failure is rather low.Compared with the alloy subjected to the single-stage aging treatment,the strength of the alloy subjected to the double-stage aging treatment decreases,but the elongation gets improved.In the retrogression and reaging state,the strength of the alloy is close to that in the single-stage aging state,and the elongation of the alloy is similar to that in the double-stage aging state.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2016年第9期41-44,共4页
Transactions of Materials and Heat Treatment
基金
博士科研启动基金(20141068)
