摘要
An ultrafine-grained Al−Zn−Mg−Zr alloy with superior mechanical performance was obtained by high passes of equal angular pressing(ECAP)and subsequent aging.After 8 ECAP passes and aging,the yield strength(YS)and ultimate tensile strength(UTS)of the solid-solutioned alloy are significantly improved from(98±10)and(226±7)MPa to(405±9)and(427±9)MPa,respectively.A large elongation is also maintained((17.4±2.5)%).The microstructure features including grain refinement,morphology of precipitates,and dislocation density,were revealed with multiscale characterizations,including transmission electron microscopy,electron backscattered diffraction,and X-ray diffraction.After 8 passes of ECAP,the original coarse elongated grains are refined to a unique bimodal grain structure consisting of ultrafine equiaxed and lath-like grains.Additionally,the effects of ECAP and subsequent aging on the strengthening contribution of a variety of strengthening mechanisms,such as dislocation strengthening and precipitation strengthening,were discussed in detail.
通过多道次等通道转角挤压(ECAP)及后续时效制备具有超细晶结构的高强韧Al-Zn-Mg-Zr合金。在经过8道次ECAP和后续时效后,固溶态合金的屈服强度和抗拉强度分别由(98±10)MPa和(226±7)MPa显著提升到(405±7)MPa和(427±9)MPa,同时合金能保持较好的伸长率((17.4±2.5)%)。采用多尺度表征手段(透射电镜、背散射电子衍射和X射线衍射)揭示合金的微观结构(包括晶粒细化、析出相形貌和位错密度)在ECAP和后续时效中的演变。经过8道次ECAP后,原本粗大的长晶粒被细化成独特的双晶粒结构(由极细等轴晶和条状晶粒组成)。同时,具体讨论一系列强化效应(例如:位错强化和析出强化)在ECAP和后续时效中的作用。
基金
financially supported by the National Key Research and Development Plan,China(No.2021YFC1910500)。
