19 research outputs found
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Fracture toughness of irradiated candidate materials for ITER first wall/blanket structures
Disk compact specimens of candidate materials for first wall/blanket structures in ITER have been irradiated to damage levels of about 3 dpa at nominal irradiation temperatures of either 90 or 250{degrees}C. These specimens have been tested over a temperature range from 20 to 250{degrees}C to determine J-integral values and tearing moduli. The results show that irradiation at these temperatures reduces the fracture toughness of austenitic stainless steels, but the toughness remains quite high. The toughness decreases as the test temperature increases. Irradiation at 250{degrees}C is more damaging than at 90{degrees}C, causing larger decreases in the fracture toughness. Ferritic-martensitic steels are embrittled by the irradiation, and show the lowest toughness at room temperature
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Cemented NbC-Co for geothermal drilling applications
Sintering and hot isostatic pressing were explored to produce a range of NbC-Co materials. Stoichiometric NbC-10Co and NbC-20Co were sintered close to the theoretical density relatively easily. Cemented NbC{sub 0.83}-10Co and NbC{sub 0.83}-20Co were more difficult to process. Some dense materials were prepared by a combination of sintering and hot isostatic pressing at 1420{degrees} to 1450{degrees}C. The carbide in these samples appeared to have the composition NbC{sub 0.9}. Hardness, toughness,and wear tests showed that the properties of these NbC{sub 0.9}-10Co samples were inferior to those of NbC{sub 0.83}-10Co materials produced previously by hot pressing. We concluded that contamination from WC milling balls and excessive processing times were the main causes of the difficulty in controlling the composition and properties of substoichiometric cemented niobium carbide. 3 figs., 7 tabs