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研究时效Al-Cu合金强塑性变形后退火过程中的显微组织与性能的变化。制备分别只含θ″、θ′和θ相的时效Al-Cu合金,在室温多向压缩变形(MAC)后进行低温退火,测试合金的拉伸性能,借助X射线衍射仪和透射电镜分析显微结构的变化。结果表明,合金中含θ″相和含θ′相试样分别在MAC变形8道次和12道次时,析出相完全回溶于基体,形成过饱和固溶体。在退火过程中,基体发生回复,并伴随粒子再次析出,产生析出强化,再析出速度比同温度下的常规时效快。在120℃退火时,析出相完全回溶的含θ″相试样和含θ′相试样的强度分别在前60和30 min上升,而析出相未回溶的含θ相试样的强度则下降;在150℃退火时,析出相完全回溶的含θ″相试样和含θ′相试样强度与退火前强度基本持平,而析出相未回溶的含θ相试样强度明显下降;在200℃退火时,析出相回溶的试样和未回溶的试样强度都出现明显下降。说明强变形Al-Cu合金退火时强度取决于析出强化与回复软化的综合作用。在所有试样中,MAC变形8道次的含θ″相试样在120℃下退火60 min,表现出最好的综合性能。
The microstructures and properties of aged Al-Cu alloys after annealing under high plastic deformation were studied. The aging Al-Cu alloys containing only θ “, θ ’and θ phases were prepared and then subjected to low temperature annealing after multiaxial compressive deformation (MAC) at room temperature. The tensile properties of the alloys were tested by X-ray diffractometry and transmission electron microscopy The results show that when the θ ”phase and θ ’phase-containing alloys in the alloy are deformed 8 times and 12 times respectively, the precipitates are completely dissolved in the matrix to form a supersaturated solid solution. In the annealing process, the matrix is restored, and with the particles precipitated again, resulting precipitation precipitation, and then the precipitation rate at the same temperature than the conventional aging fast. When annealed at 120 ℃, the strength of the θ “-phase sample and the θ ’-phase sample which were completely dissolved in the precipitates rose in the first 60 and 30 minutes, respectively, while the intensity of the θ phase-containing sample in which the precipitated phase did not dissolve The temperature of the specimen containing θ ”phase and the phase containing θ ’phase are almost the same as that of the specimen before annealing, while the strength of the phase-containing θ phase specimen is not obvious Decreased; when annealed at 200 ℃, the strength of the precipitated phase and the undissolved sample both decreased obviously. It shows that the strength of Al-Cu alloy with strong deformation depends on the combined effect of precipitation hardening and softening recovery. In all samples, the MAC-deformed 8-pass θ "-phase sample was annealed at 120 ° C for 60 min, showing the best overall performance.