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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。
A kind of strontium-scandium composite micro-alloyed 2099 Al-Li alloy (its chemical composition is Al-2.57) was studied by Vickers hardness tester, OM and SEM. Cu-1.86Li-1.31Zn-0.420Mg-0.321Mn-0.0735Zr-0.0943Sr-0.0433Sc) in the intergranular and exfoliation corrosion properties. The results show that the alloy is treated by homogenization annealing (475 ℃ × 24 h), hot forging deformation treatment (three deformations are about 100%), solution treatment (540 ℃ × 2 h), cold water quenching 5 ℃) and T8 aging treatment (121 ℃ × 14 h + 151 ℃ × 48 h), the microhardness of the alloy reaches 174.6 HV, which is higher than that of 2024-T6 alloy (solution treatment 500 ℃ × 2 h + aging treatment 191 ℃ × 12 h) is 23.1% higher. The alloy has good intergranular corrosion resistance and anti-spalling corrosion resistance, and its corrosion resistance is obviously better than 2024-T6 alloy. The alloy micro-alloying effect of Sr, Zr, Sc (refined coarse second phase, inhibition of recrystallization and grain growth), the second phase dispersion, the distribution is not continuous, and the high content of Zn is alloy corrosion resistance The main reason for high performance. The results also show that adding transition metal Sr, Sc with micro-alloying effect on Al-Li alloy is an effective way to obtain Al-Li alloy with good corrosion resistance.