预时效对高强铝锂合金2A97组织和性能的影响

以高强Al-Cu-Li-X铝锂合金2A97为研究对象,采用拉伸试验、TEM和SEM等手段测试分析了带有预时效双级时效合金组织和性能.结果表明:淬火后的双级时效和淬火变形后的双级时效,由于在终时效前增加预时效,使合金塑性提高,但强度略有下降.淬火变形后预时效过程形成的位错环和变形导致的位错有相同的作用,增加基体T1(Al2CuLi)相数量,使T1分布更均匀,淬火变形后双级时效获得T1,θ′和δ′的混合组织,同时预时效减小晶界T1尺寸.淬火后预时效导致的空位团和位错环增加基体δ′和T1形核,但数量有限,预时效有利于促进溶质原子团簇形成,增加δ′(Al3Li)和θ″(Al2Cu)析出相形核,并有利于...

Effect of Pre-Aging on Microstructure and Properties of High-Strength 2A97 Al-Cu-Li-X Alloys

The high-strength 2A97 Al-Cu-Li-X alloys were investigated for the pre-aging effect on their mechanical properties and microstructures by means of tensile test, TEM and SEM. The results showed that the double-aging effect can enhance the alloys' plasticity due to pre-aging after quenching and quenching distortion, with the strength slightly lowers. The dislocation loops due to pre-aging after quenching distortion and the dislocation brought about by the distortion have the same effect, i.e. increasing the amount of T1(Al2CuLi) phases in matrix to distribute them more evenly. The polyphase microstructure consisting of T1, δ′ and θ′ was found due to double-aging after quenching distortion, with the size of T1 precipitates on grain boundary decrease due to pre-aging. Dislocation loops and vacancy clusters caused by pre-aging may nucleate δ′ and T1 in matrix with limited amount after quenching, and the pre-aging effect accelerates the formation of clusters of solute atoms, and increases the amount of nucleated δ′(Al3Li)/θ″ (Al2Cu) precipitates and make their sizes stable. After quenching the polyphase microstructure consisting of T1, δ′ and θ′/θ″ due to double-aging was found, where the amount of precipitates T1 on grain boundary decreases with δ′-free precipitation zones on the grain boundary narrowed clearly.