中文摘要：

研究了Al-Cu二元合金的θ′相在ECAP强变形中的碎化及溶解行为。X射线衍射分析表明，ECAP变形至8道次时θ′的衍射峰消失。透射电镜观察表明，在切应力作用下矿相发生弯曲变形，内部形成了位错墙、亚晶、剪切带及扭转带结构。矿相首先在亚晶界面、剪切带及扭转带与基体的界面结合处发生溶解，继而断裂碎化及球化，并逐渐发生分解溶入基体。分析表明，θ′相在强变形中的碎化和溶解主要是由其自身的应变引起的，而并非碎化后的表面能升高。

英文摘要：

The behavior of fragmentation and dissolution of θ′ phase during ECAP severe plastic deformation has been investigated. The X-ray diffraction result showed that diffraction peak corresponding to θ′ phase disappeared after samples underwent 8 passes of ECAP deformation. The results of TEM observation suggested that under the action of shear stress created in ECAP deformation bending deformation of θ′ phase started to occur, by which a series of microstructure such as dislocation wall, subgrain boundary, shear band and torsion band structure were formed in θ′ phase. The dissolution of θ′ phase in matrix preferentially occurs at the junction point between subgrain boundary, shear band, torsion band structure and matrix. Subsequently θ′ phase was fragmentated into chain-shaped, sphericized particles and gradually decomposed to dissolve in matrix. It is indicated that the fragmentation and dissolution of θ′ phase during ECAP severe plastic deformation are mainly caused by raise of strain energy in θ′ phase instead of surface energy caused by fragmentation of θ′ phase.