Luan Baifeng

HETEROGENEOUS MICROSTRUCTURE AND TEXTURE EVOLUTION DURING FABRICATION OF Zr-Sn-Nb ZIRCONIUM ALLOY SHEETS

Zirconium alloys are widely used as fuel cladding and structural materials for nuclear reactors due to the low neutron absorption cross-section, good corrosion resistance and acceptable mechanical properties. These properties are greatly dependent on microstructural and textural features, such as grain morphology, grain size, crystallographic texture and distribution of precipitates. It is necessary to understand microstructure and texture evolution during fabrication in order to optimize the manufacturing process and to improve the service performance. In this work, microstructure and texture evolution during fabrication of Zr-Sn-Nb new zirconium alloy sheets are investigated using XRD, SEM-ECC, TEM and EBSD. The results show that the random texture formed by β quenching transforms into tilt basal texture after hot rolling. The basal texture keeps stable during the following利用XRD,SEM-ECC,TEM和EBSD技术,研究了Zr-Sn-Nb系新型锆合金板材加工过程的微观组织及织构演变.结果表明,β相淬火得到的随机织构经热轧后形成沿横向倾斜的基面织构,随后的加工过程均保留该织构;热轧及两次冷轧后的基面织构都为〈1010〉方向平行于轧向（〈1010〉//RD）,而退火后转变为〈1210〉方向平行于轧向（〈1210〉//RD）.淬火形成的网状魏氏组织经热轧转变为不均匀形变组织,两次冷轧使组织的不均匀性更显著,最终退火得到完全再结晶组织;轧制形成的难变形晶粒多为晶粒C轴平行于轧板法向（C//ND）的取向;最终退火板材的大晶粒多为〈1210〉//RD的基面织构,小晶粒则以〈1010〉//RD为主.结合锆合金的变形及再结晶机制对轧制时产生的不均匀组织及再结晶过程的织构转变进行了分析.

Study on Deformation Structure and Texture of Pure Zirconium with Large Grain Size Rolled at Liquid Nitrogen Temperature

Abstract The microstructure and the twinning behavior of the commercial pure zirconium with large grain sizes rolled 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{112}>11 10 11 11