Effect of pre-deformation on mechanical and corrosion properties of spray deposited Al-Cu-Li alloy
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摘要: 采用微观组织观察与力学和晶间性能测试相结合的实验方法，研究预变形处理（预轧制和预拉伸）对Al-Cu-Li合金后续峰值时效态合金的微观组织、力学性能以及腐蚀行为的影响。结果表明：时效前进行预变形处理能够促进合金晶粒内部析出大量均匀细小呈弥散分布的T1相，减少晶界上析出相数量，提升合金综合力学性能；析出相能够平衡合金晶界和晶粒内部的电位差，降低合金的晶间腐蚀敏感性，减小腐蚀速率，增强合金抗晶间腐蚀性能。
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关键词:
- 预变形 /
- 喷射成形Al-Cu-Li合金 /
- 微观组织 /
- 力学性能 /
- 晶间腐蚀
Abstract: The effects of pre-rolling and pre-stretching deformation on microstructure, mechanical properties and corrosion behavior of Al-Cu-Li alloy in subsequent peak-aging were investigated by means of microstructure observation with mechanical and intergranular properties tests. The test results show that the pre-deformation treatment before aging promotes the precipitation of a large number of uniform and fine T1 phase with dispersed distribution in the alloy grain, and reduces the number of precipitates on the grain boundary, so as to improve the comprehensive mechanical properties of the alloy. In addition, this precipitate microstructure can balance the potential difference between the grain boundary and the grain interior, reduce the intergranular corrosion sensitivity of the alloy, reduce the corrosion rate and enhance the intergranular corrosion resistance of the alloy. -
图 2 AA、RA、SA三种时效制度下的时效硬化曲线
Figure 2. Age hardening curves under three ageing systems of AA, RA and SA
图 3 AA、RA、SA三种时效制度下力学性能测试结果 （a）应力-应变曲线; （b）抗拉强度、屈服强度、伸长率的比较
Figure 3. Mechanical properties of AA, RA and SA under three ageing systems (a) stress-strain curve, (b) comparison of tensile strength, yield strength and elongation of three aging systems
图 4 室温拉伸实验后试样的断口形貌 （a）AA; （b）RA; （c）SA
Figure 4. Fracture morphologies of the samples after room temperature tensile tests (a) AA, (b) RA, (c) SA
图 5 试样在IGC溶液中浸泡6 h后的典型截面形貌和腐蚀深度统计 （a）AA; （b）RA; （c）SA; （d） 腐蚀深度统计
Figure 5. Cross sections of peak-aged samples undertaken different aging treatments after immersed in ICG solution for 6 h (a) AA； (b) RA； (c) SA； (d) corrosion depth statistics
图 6 HAADF-STEM图像及其对应[110]Al方向的SAED （a） [110]Al方向的SADE衍射斑点示意图; （b）AA; （c） RA; （d） SA
Figure 6. HAADF-STEM images taken along [110]Al direction and the corresponding SAED patterns (a) schematic diagrams of SADE diffraction spots in [110]Al direction, (b) AA, (c)RA, (d) SA
图 7 不同时效制度下Al-Cu-Li合金的屈服强度组成分布
Figure 7. Main component distribution of yield strength of Al-Cu-Li alloy under different aging systems
图 8 不同时效制度下试样的晶界HAADF-STEM图像 （a）AA; （b） RA; （c） SA
Figure 8. HAADF-STEM images of grain boundaries of samples under different aging systems (a) AA, (b)RA,(c) SA
图 9 不同时效制度下合金的电化学极化曲线
Figure 9. Electrochemical polarization curves of the alloys under different aging systems
表 1 Al-Cu-Li合金的标准化学成分(质量分数/%)
Table 1. Standard chemical composition of Al-Cu-Li alloy (mass fraction%)
Cu Li Mg Ag Zr Si Fe Al 4.01 1.13 0.37 0.32 0.12 0.04 0.05 Bal 
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表 2 Al-Cu-Li合金的时效处理制度
Table 2. Aging treatment system for Al-Cu-Li alloy
Solution
treatmentPre-deformation Aging
temperatureCode 510 °C/1.5 h 0 155 °C AA Pre-rolling –5% RA Pre-stretching –5% SA
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表 3 不同时效制度下晶间腐蚀形貌特征及深度
Table 3. Intergranular corrosion morphologies and depths under different aging systems
Treatment code Corrosion mode Mean IGC depth/μm Min IGC depth/μm Max IGC depth/μm AA General IGC+Pitting 136 114 154 RA Local IGC+Pitting 109 88 118 SA Pitting 121 100 140
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表 4 三种不同时效制度下T1相相关参数统计
Table 4. T1 phase related parameter statistics with three aging conditions
Treatment code Average diameter of T1 phase /nm Area fraction of T1 phase /% Number density of T1 phase /μm2 AA 171.1 3.67 26.4 RA 37.7 4.63 173.8 SA 38.3 4.61 167.3
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表 5 不同时效制度下合金的极化曲线参数
Table 5. Polarization curve parameters of the alloys under different aging systems
Treatment code Ecorr/VSCE I/A·cm–2 AA –0.666 4.17×10–6 RA –0.626 1.79×10–6 SA –0.643 2.51×10–6
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