时效前冷变形对Al-15Zn-0.5Mg-0.5Sc合金组织及力学性能的影响  

Effect of cold deformation before aging on microstructure and mechanical properties of Al-15Zn-0.5Mg-0.5Sc alloy

作　　者：肖济金 刘崇宇[1] 石磊 孙浩鸣 张磊 Xiao Jijin;Liu Chongyu;Shi Lei;Sun Haoming;Zhang Lei(School of Materials Science and Engineering,Guilin University of Technology,Guilin Guangxi 541000,China)

机构地区：[1]桂林理工大学材料科学与工程学院,广西桂林541000

出　　处：《金属热处理》2022年第10期179-184,共6页Heat Treatment of Metals

基　　金：国家自然科学基金(52161004)。

摘　　要：对热轧态Al-15Zn-0.5Mg-0.5Sc合金进行固溶+时效和固溶+冷轧+时效处理,利用光学显微镜、扫描电镜、透射电镜和万能力学试验机等研究了各状态合金的微观组织及力学性能。结果表明,冷轧可使饱和Al-Zn固溶体分解,并动态析出Zn相,同时冷轧还促使合金晶粒细化以及位错增殖。人工时效可使合金内析出高密度η′相,而冷轧所导致的高密度位错促进了析出过程并加速了η′相向η相的转变。时效前冷轧可明显优化Al-15Zn-0.5Mg-0.5Sc合金的力学性能,Al-15Zn-0.5Mg-0.5Sc合金经固溶+冷轧+70℃人工时效后,其屈服强度和极限抗拉强度分别为413和462 MPa,其强化机理包括细晶强化、位错强化和析出强化。而120℃时效会加速位错湮灭,从而削弱位错强化效果。Solution-aging and solution-cold rolling-aging treatment were carried out for the hot rolled Al-15 Zn-0.5 Mg-0.5 Sc alloy, and microstructure and mechanical properties of the alloy were studied by optical microscope, scanning electron microscope, transmission electron microscope and universal mechanical testing machine. The results show that cold rolling can decompose the saturated Al-Zn solid solution and dynamically precipitate Zn phase. At the same time, cold rolling also promotes the grain refinement and dislocation multiplication of the alloy. Artificial aging can lead to precipitation of high density η′ phase in the alloy. The high-density dislocations caused by cold rolling promote the precipitation process and accelerate the η′ phase transformation to η phase. Cold rolling before aging can obviously optimize the mechanical properties of the Al-15 Zn-0.5 Mg-0.5 Sc alloy. After solution-cold rolling-artificial aging at 70 ℃, the yield strength and ultimate tensile strength of the Al-15 Zn-0.5 Mg-0.5 Sc alloy are 413 MPa and 462 MPa, respectively. The strengthening mechanisms include fine grain strengthening, dislocation strengthening and precipitation strengthening. However, aging at 120 ℃ will accelerate dislocation annihilation and weaken the dislocation strengthening effect of the alloy.

关 键 词：AL-ZN合金 冷变形 热处理 显微组织 力学性能 

分 类 号：TG146.21[一般工业技术—材料科学与工程]