热处理对Al-Zn-Mg-Cu-Sc-Zr合金微观组织与性能的影响

Effect of Heat Treatment on Microstructures and Mechanical Properties of Al-Zn-Mg-Cu-Sc-Zr Alloys

通过硬度、拉伸性能和导电率测试,金相显微镜和透射电镜观察,研究了热处理工艺对Al-Zn-Mg-Cu-Sc-Zr合金组织性能的影响。结果表明:最佳固溶工艺为:470℃×120min;峰值时效工艺为:120℃×24h;综合性能最佳的热处理工艺为:120℃×24h+170℃×1h+120℃×24h的回归再时效处理(RRA)。经RRA处理,其抗拉强度为595.8MPa,屈服强度为572.0MPa,伸长率为8.3%,导电率为38.45%IACS。合金具有明显的时效硬化特性,其强化的主要机制是沉淀强化、细晶强化和亚结构强化,合金的主要强化相为GP区、η′和Al3(Sc,Zr)。

The microstructures and mechanical properties of Al-Zn-Mg-Cu-Sc-Zr alloys under different treatment conditions were studied by hardness test, tensile properties and electric conductivity, optical microscope and TEM observation. The result shows that the suitable solution treatment is solution at 470℃ for 120min, The peak ageing occurs at 120℃ for 24h. When the ageing treatment is RRA treatment （Retrogression and Re-ageing）： 120℃×24h＋170℃×1h＋120℃×24h, the synthetic properties is best. At this condition, the tensile strength, yield strength, elongation and electric conductivity of studied alloy are 595.8 MPa, 572.0 MPa, 8.3% and 38.45%IACS respectively. The age hardening of the studied alloys is obvious. The main strengthening mechanisms of the alloy are precipitation hardening, fine-grain strengthening and substructure strengthening. The main strengthening phases are GP zone, η＇ and Al3（Sc, Zr）.