7055铝合金中纳米析出相的演变行为

Evolution behavior of nanoscale precipitates of 7055 aluminum alloy

采用透射电镜(TEM)和高分辨透射电镜(HRTEM)研究了7055铝合金的时效强化相均匀析出行为及析出相演变过程。结果表明:在160℃单级时效时,随着时效时间从1 h延长至24 h,基体析出相逐渐增大,平均半径由2.31 nm增大至4.39 nm,晶界析出相粗化,平均长度从7.38 nm增大至20.37 nm,晶界无析出带宽化,宽度由21.36 nm增大至47.60 nm。随着单级时效时间延长,合金的强化机制由位错切过机制转化为位错绕过机制。

The uniform precipitation behavior and evolution process of aging strengthened phases of 7055 aluminum alloy were studied using transmission electron microscopy(TEM)and high-resolution transmission electron microscopy(HRTEM).The results show that during single stage aging at 160℃,as the aging time increases from 1 h to 24 h,the matrix precipitates gradually increase,the average radius increases from 2.31 nm to 4.39 nm,the precipitated phases at the grain boundaries coarsen,the average length increases from 7.38 nm to 20.37 nm,and the width of the precipitation free zone at the grain boundaries increases from 21.36 nm to 47.60 nm.As the single stage aging time increases,the strengthening mechanism of the alloy shifts from the dislocation cutting mechanism to the dislocation bypassing mechanism.