中文摘要：

主要研究大晶粒退火态纯锆在液氮温度下均匀轧制时的形变组织特征及孪生机制。利用光学显微镜、扫描电镜、电子背散射衍衬（EBSD）、X射线衍射等对不同变形量样品的变形组织和织构进行了研究,重点结合软件对EBSD结果进行组织重构和机理分析。结果表明,液氮温度轧制时大晶粒纯锆中产生的孪晶类型为C1{11 2 2}〈11 23〉、T1{10 1 2}〈10 1 1〉和T2{11 2 1}〈11 26〉孪晶,其中C1{11 2 2}〈11 23〉孪晶最容易产生且为主要孪生类型。变形开始时,3种孪晶的数量迅速增多,而小角度晶界含量较少;变形量增大到30%时,小角度晶界含量占优势。变形初始阶段孪生优先于滑移进行,且孪生变形是最主要的变形方式,当变形量为30%时,孪晶协调的位错滑移成为主要的变形方式。变形过程中织构类型未发生变化,保持基面双峰织构（偏离ND方向±30°左右）,但强度随着变形量的增大呈减小趋势。

英文摘要：

The microstructure and the twinning behavior of the commercial pure zirconium with large grain sizes roiled uniformly at 77 K were studied. The deformation structures and the textures of samples with different rolling reductions were investigated by optical microscopy, scanning electron microscopy, electron backscattering diffraction （EBSD） and X-ray diffractometer. The EBSD results show that three types of twins, including C1 {1122}〈112-3〉 compressive twins, T1{ 1012}〈10TT〉 and T2{1121 }〈112-6〉 tensile twins, occur during the rolling and the C1 { 112 2 } 〈112-3〉 compressive twins are the main twinning type. At the initial stage of the deformation, an amount of twins appear rapidly with only a few low-angle boundaries, indicating that twinning is favorable compared with dislocation slip. As the deformation reduction increases to 30%, however, a large number of low-angle boundaries are produced. It seems that the dislocation slip accommodated by twinning becomes the main deformation mechanism when the deformation reduction reaches approximately 30%. With the increase of the deformation no significant change on the texture type has been observed except slightly reduced intensity.