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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。
The effects of single-stage aging, two-stage aging and regression re-aging (RRA) process on the microstructure and properties of ultra-high strength Al-Zn-Cu-Mg-Zr alloys containing Sc were investigated by transmission electron microscopy, mechanical properties and electrical conductivity tests. The results show that the strength of the alloy decreases sharply and the electrical conductivity increases significantly after the two-stage aging treatment (120 ℃ × 8 h + 160 ℃ × 16 h). The microstructure of the alloy begins to coarsen, Continued distribution, no precipitate precipitation zone (PFZ) formation. After RRA treatment (120 ℃ × 24 h pre-aging + 180 ℃ × 30 min regression treatment + 120 ℃ × 24 h final aging), the alloy can maintain the strength close to the T6 state and obtain the higher conductivity. The crystal Within the precipitated tissue and T6 state similar to the organization, while the grain boundary precipitated phase aggregation, coarsening, and overaged organizations similar.