块体纳米晶铝的力学性能及变形机理

发布时间：2018-01-18 15:21

  本文关键词：块体纳米晶铝的力学性能及变形机理　出处：《航空材料学报》2015年03期 　论文类型：期刊论文

  更多相关文章： 纳米晶 纯铝 力学性能 变形机理 高强度

【摘要】：采用雾化粉体+挤压(Ato+Ext)、雾化粉体+热等静压+挤压(Ato+HIP+Ext)、低温球磨+挤压(Cryo+Ext)、低温球磨+热等静压+挤压(Cryo+HIP+Ext)四组不同的工艺制备块体纳米晶/细晶铝,并测定了室温拉伸性能,分析了这些块体材料的拉伸应力-应变曲线,利用透射电镜和扫描电镜观察了试样断口附近的位错活动及试样的断口形貌,讨论了其变形机理和断裂机理。研究结果表明:球磨粉体制备的块体纳米晶铝的强度远高于雾化粉体制备的块体超细晶铝,四组块体材料在拉伸过程中均不存在加工硬化现象;块体超细晶铝在拉伸过程中发生了明显的位错运动,对于块体纳米晶铝,尺寸≤100nm的晶粒在拉伸过程中内部基本不发生位错运动;块体超细晶铝大部分区域发生穿晶断裂,而块体纳米晶铝基本发生沿晶断裂。
[Abstract]:The atomized powder was extruded by hot isostatic pressing (ATO HIP Ext), and the low temperature ball milling was used to extrude Cryo Ext. The bulk nanocrystalline / fine-grained aluminum was prepared by four different processes of low temperature ball milling and hot isostatic extrusion (Cryo HIP Ext), and the tensile properties at room temperature were measured. The tensile stress-strain curves of these bulk materials were analyzed. The dislocation activity near the fracture surface and the fracture morphology of the samples were observed by transmission electron microscopy and scanning electron microscope. The deformation mechanism and fracture mechanism are discussed. The results show that the strength of bulk nanocrystalline aluminum prepared by ball milling powder is much higher than that of bulk ultrafine grain aluminum prepared by atomized powder. There is no work hardening phenomenon in the tensile process of the four groups of bulk materials. There is obvious dislocation movement in the tensile process of bulk ultrafine grain aluminum. For bulk nanocrystalline aluminum, there is no dislocation movement in the grain size 鈮，

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