1460铝锂合金的力学性能与微观组织

摘要

The as-cast structure, mechanical properties and microstructural evolution of 1460 Al-Li alloy sheet during T6 one-step aging at 160℃ and T8 two-step aging (5% predeformation followed by aging at 130℃ and then 160℃) were investigated by using metallographic microscopy, tensile measurement and tansmission electronic microscopy(TEM).The results show that the dendritic structure of cast ingot is eliminated and equi-axed grains with fine size of 20-50μm are formed due to the formation of primary crystal particle Al3(Sc,Zr) during solidification process. Meanwhile, the solutionized sheet is featured with fine elongated grain structure. The main aging precipitate of 1460 Al-Li alloy isδ′ (Al3Li), but considerable T1 (Al2CuLi) phases are also precipitated. Transitional phase ofθ″(orθ′) (Al2Cu) is formed during the aging process. In the under-aging stage,δ′ phases are precipitated rapidly. With the increase of aging time, the transitional phase ofθ″(θ′) is precipitated. Finally, T1 precipitates are formed and transitional phase ofθ″(θ′) disappears. Compared to the T6 aging, T1 precipitates with higher population density and smaller size are formed in the T8 aging, the strength of the T8-aged alloy is therefore enhanced.%采用金相观察、拉伸性能测试及透射电镜分析等手段研究1460铝锂合金的铸态组织、薄板T6态单级时效(160℃)及T8态双级时效(5%预变形,130℃+160℃时效)处理时力学性能及微观组织的演化.研究结果表明:添加微量Sc元素时,凝固时形成Al3(Sc,Zr)初生相粒子,1460铝锂合金铸锭树枝晶组织被消除,晶粒呈等轴状,粒度较小(20~50μm);而冷轧薄板固溶处理后为细小的带状晶粒组织;1460铝锂合金主要时效析出强化相为δ′相(Al3Li),其次为T1相(Al2CuLi),但在时效过程中可能形成θ″(θ′)(Al2Cu)过渡相;在时效过程中,时效前期快速析出δ′相;随时效时间延长,δ′相长大,并析出θ″(θ′)过渡相;随着时效时间进一步延长,T1相析出,而θ″(θ′)过渡相消失;与T6态时效相比,T8态时效时T1相尺寸降低但密度增大,强度提高.