添加纳米Y2O3的ODS-HT9钢的显微结构和性能

为了研究纳米Y₂O₃对HT9钢的显微结构和力学性能的影响，采用粉末冶金工艺，制备了纳米Y₂O₃含量为0.1%~0.9%的ODS-HT9钢样品，测定了样品的抗拉强度、伸长率、维氏硬度等力学性能，利用透射电子显微镜（TEM）观察和分析了样品中纳米Y₂O₃颗粒的分布状况、形状和相结构，利用扫描电子显镜（SEM）观察了样品拉伸断口的形貌。研究表明，球磨和热压烧结后，纳米Y₂O₃颗粒能够均匀地分布于基体中，相结构和形状未发生明显变化。弥散分布的纳米Y₂O₃硬质颗粒，具有明显的弥散强化作用，导致ODS-HT9钢的抗拉强度和维氏硬度随Y₂O₃含量的增加而显著增加，伸长率显著降低。Y₂O₃含量低于0.7%时，样品以韧性断裂为主，进一步增加含量，断裂方式将由韧性断裂转变成脆性断裂。纳米Y₂O₃含量为0.3%~0.5%的ODS-HT9钢，抗拉强度达到了913~936 MPa，伸长率为10.7%~11.2%，具有良好的综合力学性能。本文研究结果有助于ODS-HT9钢高温性能的研究及其在反应堆中的实际应用。 

Effect of Nano-Y2O3 on Microstructure and Properties of ODS-HT9 Steel

By power metallurgy method, the samples of ODS-HT9 steel, which were strengthened by dispersion oxide of 0.1%~0.9% Y₂O₃, were prepared in order to study the effect of nano-Y₂O₃ on the microstructure and mechanical properties of HT9 steel. The HV, tensile strength, and elongation of the samples were measured. The distribution, the shape, and the phase structure of Nano-Y₂O₃ oxide particles in the sample were observed by transmission electron microscope (TEM), and the fracture microscope was by scanning electron(SEM). The results show that Y₂O₃ particles were homogenously distributed on the HT9 steel, and their shape and phase structure have no change after ball milling and hot-pressing. Due to the strengthened dispersion of nano-Y₂O₃ particles, the tensile strength and Vickers hardness of ODS-HT9 steel increase, and the elongation decreases, significantly, with the increasing of Y₂O₃ addition. If the addition of Y₂O₃ is less than 0.7%, the fracture of samples is ductile. But, if the addition of Y₂O₃ increases furthermore, the fracture will change to brittle. The ODS-HT9 steel samples with 0.3%~0.5%(mass fraction) of Y₂O₃ have a better properties. The tensile strength and elongation reach to 913~936 MPa and 10.7%~11.2%, respectively. The results will be helpful to the study of ODS-HT9 high temperature performance and its practical application in reactors.