研究了ECAP变形后的超细晶紫铜在恒应力幅控制条件下的疲劳寿命和循环形变行为。通过电子背散射观察了疲劳前后晶粒尺寸的变化，同时通过TME观察了疲劳试样表面的滑移带。研究表明，超细晶紫铜具有较高的疲劳极限σ =153MPa，在低周疲劳域内表现出疲劳软化，而在高周疲劳域内表现比较稳定的疲劳行为，甚至出现疲劳硬化。类似驻留滑移带（PSB）的剪切带与最后一次挤压的剪切面一致，是疲劳裂纹形核和疲劳断裂的主要原因。
The fatigue life and cyclic deformation behavior of UFG copper produced by ECAP is studied in this paper. The changes of the grain size and the development of slip bands are observed by means of electron back scattering diffraction and TEM, respectively. The result shows that the fatigue limit of the UFG copper corresponding to 107 cycles is 153MPa. Cyclic softening occurs in the low-cycle fatigue region whereas stable cyclic behavior or even cyclic hardening occurs in the high-cycle region. Persistent slip bands (PSB)-like shear bands (SBs) were approximately parallel to the shearing plane of last pressing. The formation of SBs is the main factor causing crack nucleation as well as premature failure.
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