通过透射电镜分析、力学性能和电导率测试,研究了单级时效、双级时效和回归再时效（RRA）工艺对含Sc超高强Al-Zn-Cu-Mg-Zr合金组织与性能的影响。结果表明：经（120℃×8 h＋160℃×16 h）双级时效处理后,合金的强度大幅下降,而电导率显著升高;其晶内组织开始粗化,晶界析出相呈断续状分布,无沉淀析出带（PFZ）形成。经（120℃×24 h预时效＋180℃×30min回归处理＋120℃×24 h终时效）RRA处理后,合金既能保持接近T6态的强度,也能获得较高的电导率;其晶内析出组织与T6态的组织类似,而晶界析出相则聚集、粗化,与过时效的组织相似。
Effects of single aging,duplex aging and retrogression and reaging（RRA） treatments on microstructure and mechanical properties of the Al-Zn-Cu-Mg-Zr alloy containing Sc were studied by means of transmission electron microscopy,tensile test and conductivity measurement.The results show that after duplex aging of 120 ℃×8 h＋160 ℃×16 h,strength of the alloy decreases sharply and its conductivity rises quickly,and grains of the alloy becomes coarse obviously,and the precipitates at grain boundary grow up with discontinuous distribution.The alloy maintains the strength level of T6 and a high conductivity value after the RRA treatment,which is pre-aging at 120 ℃ for 24 h,retrogression at 180 ℃ for 30 min and re-aging at 120 ℃ for 24 h.The precipitates in grains are similar to those after T6 temper and the grain boundary precipitates are similar to those of over-aged condition for the alloy after the RRA treatment.
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