Hardening of an ODS Ferritic Steel after Helium Implantation and Thermal Annealing

Specimens of an oxide dispersion strengthened(ODS) ferritic steel(15 Cr-4 Al-0.6 Zr-0.1 Ti) are implanted with multiple-energy He ions at room temperature to create a damage plateau of 0.4 dpa for the average(corresponding to an He concentration of about 7000 appm) from the near surface to a depth about 1 um. The specimen is subsequently thermally annealed at 800°C for 1 h in a vacuum so that simple defects can be formed in the as-implanted state that has undergone significant recombination, meanwhile helium bubbles at nano-scale are formed. Hardness of the specimens are tested with the nano-indentation technique. A hardening by 25% is observed. Microstructures of the specimen after irradiation/annealing are investigated with transmission electron microscopy. Helium bubbles are generally located at dislocations and grain boundaries. Using the dispersed barrier strength model, the strength factor of helium bubbles in the ODS ferritic steel is estimated to be between0.1 and 0.26, which is close to that of helium bubbles in austenitic steels.     

碳化硅中氦离子高温注入引入的缺陷及其退火行为的光谱研究

对氦（He）离子高温（600 K）注入6H-SiC中的辐照缺陷,在阶梯温度退火后演化行为的拉曼光谱和室温光致发光谱的特征进行了分析.这两种方法的实验结果表明,离子注入所产生晶格损伤的程度与注入剂量有关;高温退火导致损伤的恢复,不同注入剂量造成的晶格损伤需要不同的退火温度才可恢复.在阶梯温度退火下呈现出了点缺陷的复合、氦-空位团的产生、氦泡的形核、长大等特性.研究表明：高温（600 K）注入在一定剂量范围内是避免注入层非晶化的一个重要方法,为后续利用氦离子注入空腔掩埋层吸杂或者制备低成本、低缺陷密度的绝缘层 关键词： 6H-SiC 离子注入 拉曼光谱 光致发光谱