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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：2475 下载量：352
| 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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