Wang Shuai, Luo Binghui, Bai Zhenhai, He Chuan, Tan Sizhi, Jiang Gen
Key Laboratory for Nonferrous Materials (MOE), School of Materials Science and Engineering, Central South University, Changsha 410083, China.
Materials (Basel). 2019 Jan 16;12(2):285. doi: 10.3390/ma12020285.
The effects of different Zn/Mg ratios on the microstructure, mechanical properties and resistance of stress corrosion cracking of peak-aged 7005 aluminum alloy were investigated. It was found that the Zn/Mg ratio played a very important role in controlling the aging time, the electrical conductivity of the hardness peak point and the resistance of stress corrosion cracking of the alloy. With the increase of Zn/Mg ratio (wt. %), the time taken by the alloy to achieve the peak hardness value gradually increases aging at 120 °C. When the Zn/Mg ratio is in the range from 2.27% to 2.62%, the precipitate phase of the alloy after peak-aged is mainly dominated by smaller disc-like η' phase and GP I (Guinier Preston) zones, the grain boundary precipitates are slender and continuous and the PFZ (precipitate free zones) is narrow. However when this value is in the range from 3.01% to 4.08%, precipitation phase in matrix of the alloy is mainly composed of short-rod η' phase and GP II zones, the precipitation phases within the grain boundary are large and distribute intermittently and the PFZ is narrower. The results of SSRT (slow strain rate tests) show that when Zn/Mg ≥ 3.61, the 7005 aluminum alloy at peak-aged has good resistance of stress corrosion cracking in 3.5% NaCl + 0.5% H₂O₂ aqueous solution. However, when Zn/Mg ≤ 3.01, the strength of the alloy sharply decreases in 3.5% (wt. %) NaCl + 0.5% (wt. %) H₂O₂ aqueous solution.
研究了不同锌/镁比对峰值时效7005铝合金微观组织、力学性能及应力腐蚀开裂抗力的影响。结果表明，锌/镁比在控制合金的时效时间、硬度峰值点的电导率以及应力腐蚀开裂抗力方面起着非常重要的作用。随着锌/镁比（质量分数）的增加，合金在120℃时效达到峰值硬度值所需的时间逐渐增加。当锌/镁比在2.27%至2.62%范围内时，峰值时效后合金的析出相主要以较小的盘状η'相和GP I（吉尼尔-普雷斯顿）区为主，晶界析出物细长且连续，无析出带（PFZ）较窄。然而，当该值在3.01%至4.08%范围内时，合金基体中的析出相主要由短棒状η'相和GP II区组成，晶界内的析出相较大且呈间歇性分布，PFZ较窄。慢应变速率试验（SSRT）结果表明，当锌/镁比≥3.61时，峰值时效的7005铝合金在3.5%NaCl + 0.5%H₂O₂水溶液中具有良好的应力腐蚀开裂抗力。然而，当锌/镁比≤3.01时，合金在3.5%（质量分数）NaCl + 0.5%（质量分数）H₂O₂水溶液中的强度急剧下降。
