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变形促进析出的θ’近似相对Al-Cu合金 力学性能的提高

发表时间:2017-12-29  浏览量:919  下载量:148
全部作者: 马培培,刘春辉,伍翠兰,赖玉香,刘力梅,陈江华
作者单位: 湖南大学材料科学与工程学院高分辨电镜中心
摘 要: 用显微硬度测试、拉伸试验、透射电子显微镜(transmission electron microscope,TEM)和原子尺度的环形暗场扫描透射电子显微镜(angular dark-field scanning transmission electron microscope,ADF-STEM)等测试手段研究大的预变形对Al-Cu 合金时效硬化、力学性能和微观结构的影响。结果表明,在后续的时效过程中,经过80%冷轧变形的合金比传统T6 工艺制备的Al-Cu 合金强度提高了35%,并且塑性得到了很好的保持。在150℃时效后,合金中仍然保留冷轧过程引入的大量位错。一般认为冷轧Al-Cu 合金中高密度位错墙和位错缠结会导致材料微观结构的不均匀性,但是这种沿基体(001)面析出的盘片状相却表现出非常均匀的分布。ADF-STEM 观察发现这种析出相与θ\\\\\\\'相晶体结构类似,但是其体心位置的Cu 原子是缺失的,本文称之为θ\\\\\\\'近似相。此外,析出相尺寸相比T6 峰值的样品明显细化。这种形变改性的析出可能对合金的强度-塑性协同效应至关重要。
关 键 词: 金属材料;Al-Cu 合金;析出相;形变;时效;透射电子显微镜
Title: Mechanical properties enhancement by deformation-modified precipitation of θ\\\'-phase approximants in Al-Cu alloy
Author: MA Peipei, LIU Chunhui, WU Cuilan, LAI Yuxiang, LIU Limei, CHEN Jianghua
Organization: Center for High-Resolution Electron Microscopy, College of Materials Science & Engineering, Hunan University
Abstract: The effect of large pre-deformation on the age hardening behaviors, tensile properties and microstructure in Al-Cu alloy during artificial ageing have been investigated using microhardness test, tensile test, transmission electron microscope (TEM) and atomic-scale angular dark-field scanning transmission electron microscopy (ADF-STEM). It is shown that in the subsequent artificial ageing process, room-temperature rolling of Al-Cu alloy with thickness reduction of 80% can result in strength increase by 35% without sacrificing ductility as compared to the alloy peak-aged by a conventional heat treatment process (T6). After post-ageing at 150℃, a large quantity of dislocations accumulated during cold-rolling is retained in Al-Cu alloy. Dense dislocation walls and dislocation tangles exists in cold-rolled Al-Cu alloy which are expected to result in microstructural heterogeneity, while the plate-shaped precipitates on (001) Al planes exhibit exceptionally uniform distribution. ADF-STEM reveals these precipitates are θ\\\'-approximants with a crystal structure similar with the well-known θ\\\' phase but with the absence of Cu atom at the body-centered position. In addition, the precipitate sizes are considerably refined as compared to the θ\\\' precipitates formed in T6 peak-aged alloys. The results suggest the deformation-modified precipitation may play a vital role in achieving better strength-ductility synergy.
Key words: metallic materials; Al-Cu alloy; precipitates; deformation; ageing; transmission electron microscope
发表期数: 2017年12月第24期
引用格式: 马培培,刘春辉,伍翠兰,等. 变形促进析出的θ’近似相对Al-Cu合金 力学性能的提高[J]. 中国科技论文在线精品论文,2017,10(24):2718-2727.
 
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