作　　者： ; ; ; ; ; ; ; ; ;

机构地区： 中南大学材料科学与工程学院

出　　处： 《中国有色金属学报》 2011年第10期2616-2630,共15页

摘　　要： 采用力学性能测试和电子显微分析技术研究了不同加工处理条件下Al-5.4Zn-2.0-Mg-0.25Cu-0.1Sc-0.1Zr合金的显微组织及性能演变。结果表明：在半连续激冷铸造条件下,铸锭存在晶界偏析,形成了富Zn、Mg的非平衡相和富Fe、Si、Mn的杂质相;经470℃、12 h均匀化处理后,富Zn、Mg的非平衡相溶入基体,仅剩下少量富Fe、Si、Mn的杂质相;与此同时,铸锭合金固溶体分解析出纳米级的Al3（Sc,Zr）相,470℃、12 h是研究合金合适的铸锭均匀化制度;铸锭热变形过程中,随试验温度升高合金强度逐渐降低,伸长率则先增加而后降低,350~400℃的温度范围内合金具有较稳定的热变形抗力和塑性,是合宜的热变形温度范围;合金冷轧板材经470℃、1 h固溶处理后,热变形过程中形成的大量非平衡相溶入基体形成过饱和固溶体,时效过程中脱溶顺序为αsss（α过饱和固溶体）→GP区→η′相→η相。合金板材最佳固溶-时效工艺为（470℃,1 h）固溶＋（120℃,24 h）时效,在此条件下,试验合金的抗拉强度、屈服强度和伸长率分别可达533 MPa、494 MPa和15%。试验合金的高强度主要来源于η′相析出强化、添加微量Sc和Zr引起的亚晶强化和亚结构强化以及Al3（Sc,Zr）相的弥散强化。 The evolution of microstructure and properties of Al-5.4Zn-2.0Mg-0.25Cu-0.1Sc-0.1Zr under different processing and heat treatment conditions was studied using mechanical properties measurement and electron microscopy.The results show that,under semi-continuous casting conditions,at grain boundaries there is some segregation which is bearing Zn,Mg non-equilibrium phases and indissoluble impurity phases containing Fe,Si and Mn elements.After the homogenization at 470 ℃ for 12 h the non-equilibrium phases dissolve into matrix completely and only small amounts of indissoluble phases still exist.At the same time,the solid solution matrix precipitates nano-scaled Al3（Sc,Zr） dispersoid particles.The proper homogenization treatment processing of the ingot is at 470 ℃ for 12 h.During the hot deformation of ingot,with the increase of deformation temperatures,the strength decreases,the elongation increases firstly and then decreases.Between 350 ℃ and 400 ℃ the alloy is of a more stable deformation characteristics and this is the suitable deformation temperature range for this alloy.After solutioning at 470 ℃ for 1 h lots of non-equilibrium phases formed during hot rolling dissolve into the matrix.The precipitation sequence of the alloy during aging is described as follows： supersaturated solid solution（α）→GP zones→metastable η′ phase→η phase.The suitable solution-aging treatment processing of the studied alloy is solution-treated at 470 ℃ for 1 h,followed by water quenching and then aged at 120 ℃ for 24 h.Under this condition,the ultimate tensile strength,yield strength and elongation of the studied alloy plate could reach 533 MPa,494 MPa and 15%,respectively.The strengthening mechanism of the studied alloy is precipitation strengthening of fine η′ phase,subgrain strengthening and dispersion strengthening caused by Al3（Sc,Zr） dispersoid particles.

关 键 词： 合金 板材 铸锭均匀化 热塑性 固溶 时效 组织 力学性能 演变

领　　域： [金属学及工艺] [一般工业技术] [金属学及工艺]