含锶钪2099型铝锂合金的晶间腐蚀和剥落腐蚀性能

采用维氏硬度计(HV)、金相显微镜(OM)和扫描电镜(SEM)显微分析技术,研究了一种锶钪复合微合金化2099型铝锂合金(其化学成分为:Al-2.57Cu-1.86Li-1.31Zn-0.420Mg-0.321Mn-0.0735Zr-0.0943Sr-0.0433Sc)的晶间腐蚀性能和剥落腐蚀性能。结果表明,该合金经均匀化退火处理(475℃×24 h)、热锻压变形加工处理(三次变形量均约为100%)、固溶处理(540℃×2 h)、冷水淬火(水温大约5℃)、T8时效处理(121℃×14 h+151℃×48 h)后,合金显微硬度值达到174.6 HV,比2024-T6合金(固溶处理500℃×2 h+时效处理191℃×12 h)高23.1%。合金具有良好的抗晶间腐蚀性能和抗剥落腐蚀性能,其抗腐蚀性能明显优于2024-T6合金。该合金Sr,Zr,Sc的复合微合金化作用(细化粗大第二相、抑制再结晶和晶粒长大),第二相分散、分布不连续,以及Zn的含量高,是合金抗腐蚀性能高的主要原因。研究结果还说明了微量复合添加对铝锂合金具有奇效微合金化作用的过渡族金属元素Sr,Sc,是得到抗腐蚀性能良好的铝锂合金的一种有效途径。

Intergranular and Exfoliation Corrosion Properties of 2099 Type Al-Li Alloy with Sr and Sc Additions

Intergranular and exfoliation corrosion properties of 2099 type Al-Li alloy(chemical composition: Al-2.57Cu-1.86Li-1.31Zn-0.420Mg-0.321Mn-0.0735Zr-0.0943Sr-0.0433Sc)containing Sr and Sc were studied by using Vickers hardness tester(HV),optical microscope(OM) and scanning electronic microscope(SEM) analysis techniques.The results showed that after annealing(475 ℃×24 h),hot forging deformation processing(every deformation volume of about 100% of three times),solid solution treatment(540 ℃×2 h),cold water quenching(water temperature about 5 ℃),and T8 aging treatment(121 ℃×14 h+151 ℃×48 h),the microhardness(~174.6 HV) of alloy was higher than 2024-T6 alloy(solid solution treatment of 500 ℃×2 h+aging treatment of 151 ℃×48 h) 23.1%.Moreover,the alloy presented superior resistance to intergranular and exfoliation corrosion,the corrosion resistance was evidently better than 2024-T6 aluminum alloy.The main reasons why the alloy had a high performance of corrosion resistance were that Sr,Zr and Sc composite microalloying refined coarse second phase,inhibited recrystallization and grain growth,the second-phases were dispersive and discontinuous,and the content of Zn was high.The results also showed that it was an effective way to obtain a good corrosion resistance of Al-Li alloys containing composite miraculous microalloying transitional metal element Sr and Sc.