Cu,Li含量对新型超高强铝锂合金力学性能及微观组织的影响

Influence of Cu and Li contents on mechanical properties and microstructures of a new super high strength Al-Li alloy

利用力学性能测试和TEM分析测试手段,计算出铝锂合金Al-(3.6%~4.15%)Cu-(1.1%~1.4%)Li中非固溶Cu,Li原子摩尔分数总和及Cu/Li原子摩尔分数比,分析了强度和微观组织之间的影响机理.结果表明,合金中的主要时效强化相为大量T1相(Al2CuLi)和少量θ′相(Al2Cu),Li含量较高的合金可能析出的极少量δ′相(Al3Li).在上述成分范围内,随Cu含量或Li含量增加,合金强度提高,且Li含量的增加幅度不同,对合金强度的提高幅度存在明显的差异.非固溶Cu,Li原子摩尔分数总和及其比例共同作用,通过影响析出相总量、类型及各析出相分数决定合金强度.要获得铝锂合金的超高强度,在提高Cu,Li原子摩尔分数总和的同时,还要提高其比例.

Based on Al-Li alloys with Cu（3.6%-4.15%） and Li（1.1%-1.4%）, the influence of Cu and Li contents on the mechanical properties and microstructures of T8 and T6 aged Al-Li alloys with microalloying elements of Mg, Ag and Zn was investigated. By using tensile properties measurement and TEM, the strengthening effect and microstructure evolution were analyzed through total non-solution atomic mole fractions of Cu and Li and their atomic ratio. The strengthening precipitates consisted of a lot of T1 （Al2CuLi）, a few θ＇（Al2Cu） and a thimbleful of δ＇ （Al3Li） which may be precipitated with high contents of Li. Strength of the alloys was enhanced with increasing the contents of Li or Cu in the range of contents above. And different increasing extent of Li content enhanced the strength of the alloy with obviously different extent. Total non-solution atomic mole fraction of Cu and Li and their ratio determined the strength of the alloy by effecting the amount, types, and fractions of precipitates. To enhance the strength of Al-Li alloys largely, their atomic ratio should be kept high values, while increasing the total non-solution atomic mole fraction of Cu and Li.