含钛氧化物弥散强化钢的微观组织和力学性能

采用粉末冶金工艺制备了含Ti氧化物弥散强化钢。使用电子背散射衍射方式研究了这种钢的晶粒形貌，使用透射电镜和高分辨率透射电镜表征了钢中析出相的形貌及种类，使用以同步辐射装置作为光源的小角度X射线散射技术和X射线吸收精细结构技术研究了钢中纳米尺寸析出相的分布特征和氧化物弥散强化钢中Y元素的存在形式，并测量了钢的力学性能。结果表明，含Ti氧化物弥散强化钢的晶粒多呈等轴状、平均晶粒尺寸为1.24 μm。钢中富Y、Ti、O纳米尺寸析出相的分布密度为1.39×10²⁴/m³，平均直径为2.23 nm。向材料中添加Ti元素改变了材料中Y原子的存在形式，生成了具有烧绿石结构的Y₂Ti₂O₇相和少量的富Cr、Mn相。这种钢的室温抗拉强度达到1324 MPa，随着测试温度的提高抗拉强度逐渐降低，延伸率逐渐提高。

Microstructure Characterization and Tensile Properties of a Ti-bearing Oxide Dispersion Strengthened Steel

An oxide dispersion strengthened (ODS) steel containing Ti was prepared by powder metallurgy. The grain morphology of the ODS steel was investigated by electron backscatter diffraction (EBSD). The morphology and types of precipitates in the ODS steel were characterized by transmission electron microscope (TEM) and high-resolution transmission electron microscope (HRTEM). The nano size precipitates of the ODS steel was investigated by small angle X-ray scattering (SAXS) technique and X-ray absorption fine structure (XAFS) technique using synchrotron radiation device. And the existence form of Y element in the ODS steel was examined by using XAFS technique. At the same time, the mechanical properties of the ODS steel were measured. The results show that the grains of the ODS steel are equiaxed, and the average grain size is 1.24×10^-6 m. The spatial density of the nano-sized precipitates rich in O, Ti and Y of the steel is 1.39×10^-24/m³, while the formed Y₂Ti₂O₇ phase presents pyrochlore structure and a small amount of a phase rich in Cr and Mn was observed too. The tensile strength of the ODS steel reaches 1324 MPa at room temperature. With the increase of test temperature, the tensile strength of the material decreases, whereas the elongation increases gradually for the ODS steel.