非等温时效工艺对7050铝合金组织和耐腐蚀性能的影响

The Effect of Non-isothermal Aging Process on Microstructure and Corrosion Resistance of 7050 Aluminum Alloy

利用蔡司正置金相显微镜、SEM、EDS、抗剥落腐蚀试验等手段研究了不同的非等温时效工艺对7050铝合金组织和耐腐蚀性能的影响。结果表明,随着终止时效温度从190℃降至130℃,晶内、晶界残余未溶的第二相粒子数目逐渐减少、尺寸逐渐减小,分布更加均匀;进一步降低终止时效温度,残余第二相粒子尺寸有所增大,第二相粒子主要为MgZn2相、Al2CuMg相和Al7Cu2Fe相;随着终止时效温度的降低,7050铝合金的耐腐蚀性能逐渐提高,在终止时效温度为130℃时表现最佳,进一步降低终止时效温度,合金的耐腐蚀性能不升反降,腐蚀经历了点蚀-沿晶腐蚀-剥落腐蚀三个过程。

The effects of different non-isothermal aging processes on the structure and corrosion resistance of 7050 aluminum alloy were studied by means of Zeiss positive metallographic microscope,SEM,EDS and exfoliation corrosion test.The results show that,with the decrease of the termination aging temperature from 190℃to 130℃,the number and size of the remaining undissolved second phase particles in grains and grain boundaries decrease gradually,and the distribution become more even.Further decreasing the termination aging temperature,the size of the remaining second phase particles increases,and the second phase particles are mainly MgZn2 phase,Al2CuMg phase and Al7Cu2Fe phase.With the decrease of termination aging temperature,the corrosion resistance of 7050 aluminum alloy is gradually improved,and the best performance is achieved at 130℃.By further reducing the termination aging temperature,the corrosion resistance of the alloy does not increase but become to decrease.The corrosion process includes pitting corrosion,intergranular corrosion and exfoliation corrosion.