中文摘要：

通过超声喷丸在Zr-4合金表面获得细晶组织，采用金相显微镜、X射线衍射（XRD）以及场发射扫描电镜（FEG-SEM）观察处理前后锆合金的晶粒组织变化。结果表明，喷丸后样品从表面到芯部依次为：纳米晶（厚度约为60μm）、超细晶（厚度约为160μm）和原始组织。喷丸处理的晶粒细化机制为剧烈塑性变形。主要过程包括：孪晶、位错萌生-位错纠缠-晶粒分割-取向随机化。

英文摘要：

A refined structure was obtained on Zircaloy-4 through ultra-sonic shot peening （USSP） treatment and characterized by optical microscopy （OM）, X-ray diffraction （XRD） and field-emission gun scanning electron microscopy （FEG-SEM）. It has been found that the treated sample consists of three grain structures： surface nanocrystalline （60μm thick）, ultrafine grain （160μm thick） and the matrix. The grain refinement mechanism is attributed to severe plastic deformation （SPD） during the USSP treaarment, which includes： formation of twins and dislocations, formation of dislocation tangles, subdivision by dislocation cells, orientation randomization.