摘要
The slip behavior and precipitation behavior of four Al−Cu−Li single crystals with varying orientations at different temperatures were investigated using electron backscattering diffraction(EBSD)and transmission electron microscopy(TEM).The maximum differences in yield strength and ductility of the single crystals at room temperature are 41.6%and 14.7%,respectively.This indicates that the mechanical properties are strongly influenced by the crystal orientation.Moreover,grains with varying orientations exhibit distinct slip characteristics,including slip homogenization,slip localization,and multiple slip.In single crystal SC1,slip localization primarily contributes to its inferior ductility compared to other grains.Nevertheless,during deformation at 250℃,the distinct morphology and distribution of precipitates in the crystals are also correlated with orientation,which causes the increase in the maximum elongation difference to 20.8%in all selected single crystals.Notably,SC1,with a precipitate volume fraction of 2.65%,exhibits more severe slip localization compared to room temperature conditions,while SC2,with a precipitate volume fraction of 4.79%,demonstrates cross-slip characteristics,significantly enhancing the plastic deformation capacity of the Al−Cu−Li alloy.
利用电子背散射衍射(EBSD)和透射电子显微镜(TEM)研究了4种不同取向的Al-Cu-Li单晶在不同温度下的滑移行为和析出行为。单晶在室温下的屈服强度和伸长率的最大差异分别为41.6%和14.7%,说明力学性能与晶体取向有很强的相关性。不同取向的单晶表现出独特的滑移特征,包括滑移均匀化、滑移局部化和多系滑移。对于单晶SC1来说,滑移局部化是导致其伸长率低于其他单晶的主要原因。然而,在250℃变形时,不同取向单晶的析出相形藐和分布存在明显差异,导致最大伸长率差异增加到20.8%。值得注意的是,与室温相比,析出相体积分数为2.65%的单晶SC1表现出更严重的滑移局部化,而析出相体积分数为4.79%的单晶SC2表现出交滑移特征,显著增强了Al-Cu-Li合金的塑性变形能力。
基金
supported by the National Natural Science Foundation of China (No.U21B6004)
Major Project of Scientific Innovation of Hunan Province,China (No.2021GK1040)
National Key R&D Program of China (No.2020YFA0711104)。
