多级均匀化处理对Al-Cu-Li-Sc-Zr合金微观组织与性能的影响EI北大核心CSCD

通过DSC测定Al-Cu-Li-Sc-Zr合金中Al_(3)(Sc,Zr)弥散相的析出温度,为确定Al_(3)(Sc,Zr)弥散相粒子析出的保温温度与保温时间,制定四种三级均匀化制度。随后将四种均匀化样品经过热轧、固溶、时效等处理后进行室温拉伸对比其力学性能,并通过样品的时效硬化曲线计算表观激活能,采用SEM与EDS分析均匀化后样品的第二相形貌与成分,EBSD表征固溶后样品的晶粒取向特征。结果表明:多级均匀化处理过程中第二阶段温度为460℃的均匀化制度相比于410℃的均匀化制度更利于Al_(3)(Sc,Zr)弥散相粒子的析出,在细化晶粒组织、抑制再结晶的同时,也促进后续时效处理过程中含Li强化相的析出,通过晶界强化、织构成分以及析出相的复合作用提升合金力学性能。另外,由于Al_(3)(Sc,Zr)弥散相粒子的析出,热变形退火后合金中大量亚晶微观组织得以保留,合金在室温拉伸过程中变形均匀,伸长率提高。

Effect of multistage homogenization treatment on microstructure and properties of Al-Cu-Li-Sc-Zr alloys

Precipitation temperature of Al₃(Sc, Zr) dispersed phase in Al-Cu-Li-Sc-Zr alloys was investigated by DSC. Four kinds of triple-step homogenization treatments were designed to obtain the holding temperature and time of Al₃(Sc, Zr) dispersed phase particles. After hot rolling, solution treatment and aging treatment, the mechanical properties of homogenized samples were compared by room temperature tensile tests. The apparent activation energy was calculated by the results of aging hardening curves, the morphology and composition of the second phase in homogenized samples were investigated by SEM and EDS, and the grain orientation characteristics of samples after solution treatments were investigated by EBSD. The results show that the Al₃(Sc, Zr) dispersed phase at 460 ℃ which is the second step temperature in homogenizations is more favorable than that at 410 ℃ during the multistage homogenization treatments, which can control grain structure, inhibit recrystallization and promote the precipitation of strengthening phase containing Li during aging treatment. The compound action of grain boundary strengthening, texture composition and precipitated phase improves the mechanical properties of the alloys. In addition, for the dispersed particles like Al₃(Sc, Zr) separated, many sub-grain microstructures are conserved after hot deformation annealing, which makes alloys deform uniformly during tensile process at room temperature and improves the ductility of the alloys.