初始状态对2124铝合金蠕变时效行为与力学性能的影响

Effect of Initial States on Creep Aging Behaviors and Mechanical Properties of 2124 Aluminum Alloy

通过光学、透射电子显微、蠕变与室温拉伸实验研究了2124铝合金板的蠕变时效行为与力学性能。结果表明:185℃/150MPa条件下,经固溶-淬火处理(QCA)板材的蠕变机制从位错增殖发展为位错增殖-消毁平衡,其蠕变曲线第一阶段与第二阶段分界点较为明显;而经固溶-淬火-预压缩处理(PCA)板材的蠕变机制主要为预压缩引入的位错消毁,蠕变曲线第一阶段特征并不明显。蠕变时效过程中,S′相的析出总是伴随着位错线形核,其析出方位受位错运动机制的影响,PCA处理初期,经预压缩引入的位错缠结使S′相可以在互相垂直的{210}面上析出,从而抑制了S′相的位向效应。PCA处理试样的力学性能优于该合金的T6和T87状态的,且各向异性小于QCA处理的。

Creep aging behaviors and mechanical properties of 2124 aluminum alloy sheets have been studied by optical microscopy（OM）,transmission election microscopy（TEM）,creep and tensile test,et al.The results show that when the creep aging at 185℃/150MPa,the turning point between the first stage and the second one along the creep curve is easily observed for the samples with an initial state of solution-water quenching（QCA）,the characters of TEM micrographics show that the dislocation multiplication（DM） and the balance between DM and dislocation annihilation（DA） occur.While the turning point along the creep curve is difficultly identified for the samples with the initial state of solution-water quenching-rolling to thickness reduction rate of 8%（PCA）,the microstructures of TEM reveal that DA mainly occurs.During the processes of creep-aging,it is found that the precipitating S′ phase particles always nucleate with dislocation lines,and their orientations are effected by characteristics of dislocation moving.During PCA process,the existing of dislocation tangling by the rolling before the creep aging supports precipitating S′ phase on vertical {210} planes,therefore,the stress orientated effect of S′ phase is restrained.The mechanical properties of PCA sample are well than that of the as T6 and T87,and the anisotropy of mechanical properties is less than that of the as QCA.