Publications (5)0 Total impact
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Article: Analysis and measurement of residual stress distribution of vanadium/ceramics joints for fusion reactor applications
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ABSTRACT: Vanadium alloys are considered as candidate structural materials for fusion reactor system. When vanadium alloys are used in fusion reactor system, joining with ceramics for insulating is one of material issues to be solved to make component of fusion reactor. In the application of ceramics/metal jointing and coating, residual stress caused by difference of thermal expansion rate between ceramics and metals is an important factor in obtaining good bonding strength and soundness of coating. In this work, residual stress distribution in direct diffusion bonded vanadium/alumina joint (jointing temperature: 1400°C) was measured by small area X-ray diffraction method. And the comparison of Finite Element Method (FEM) analysis and actual stress distribution was carried out. Tensile stress concentration at the edge of the boundary of the joint in alumina was observed. The residual stress concentration may cause cracks in alumina, or failure of bonding. Actually, cracks in alumina caused by thermal stress after bonding at 1500°C was observed. The stress concentration of the joint must be reduced to obtain good bonded joint. Lower bonding temperature or to devise the shape of the outer surface of the joint will reduce the stress concentration.Journal of Nuclear Materials. -
Article: Mechanical Properties of Mo and TZM Alloy Neutron-Irradiated at High Temperatures
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ABSTRACT: This work reports the mechanical properties of irradiated molybdenum (Mo) and its alloy, TZM. Recrystallized and stress-relieved specimens were irradiated at five temperatures between 373 and 800℃ in FFTF/MOTA to fluence levels of 6.8 to 34 dpa. Irradiation embrittlement and hardening were evaluated by three-point bend test and Vickers hardness test, respectively. Stress-relieved materials showed the enough ductility even after high fluence irradiation. The role of layered structure of stress-relieved specimen was discussed. Molybdenum Fusion materials Mechanical properties Neutron irradiation Irradiation effect -
Article: Effect of Helium Implantation on Tensile Properties of V-Ti-Cr-Si Type Alloy
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ABSTRACT: Helium implantation of 50at.ppmHe by cyclotron accelerator was adopted to study helium effect on tensile properties of the V-5Ti-5Cr-1Si-Al-Y type alloy. Tensile tests were conducted at temperatures ranging from room temperature to 850℃ with strain rates from 6.7×10^<-5> to 6.7×10^<-3>/s. Increase of yield stress was not appreciable in helium-implanted specimens except for 450℃. Intergranular fracture mode was observed specimens tested at temperatures above 450℃. Decrease of elongation was observed at all testing temperatures. Relationship between tensile strength and decrease of elongation was discussed. Vanadium alloy fusion materials low activation materials helium embrittlement tensile propertie -
Article: Low Activation V-Ti-Cr-Si Type Alloys for Fusion Applications
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ABSTRACT: V-Ti-Cr-Si type alloys containing Al and Y were prepared for structural materials application of fusion reactors. The condition of heat treatment, tensile properties and deformation microstructures were examined for two type alloys referred as V-25Ti-15Cr and V-5Ti-5Cr. The neutron irradiation behavior was also studied. Tensile test were conducted using miniature-type specimens at temperatures from 300 to 1273K. The alloy V-25Ti-15Cr showed the strength twice as high as V-5Ti-5Cr at temperatures from 300 to 873 K. Ductility of V-5Ti-5Cr alloy was larger than that of V-25Ti-15Cr at lower temperatures. The amount of void swelling after neutron irradiation of the two alloys was very low level compared with that of various vanadium alloys. -
Article: Neutron irradiation embrittlement of molybdenum rhenium alloys and their improvement by heat treatment
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ABSTRACT: Irradiation-induced embrittlement is one of the major problems with molybdenum alloys, which have been considered as one of the candidates for divertor structural materials. The effects of rhenium content, heat-treatment and irradiation condition on mechanical properties and microstructural development of molybdenum rhenium alloys were studied after neutron exposure by FFTF/MOTA up to high fluence (∼1 × 1027 n/m2, En>0.1 MeV). Appreciable plastic deformation was observed in a bending test on stress-relieved Mo–5 wt% Re irradiated at high temperatures. Fine, dense precipitates were observed in Mo–41 wt% Re, resulting in large hardening and embrittlement.Journal of Nuclear Materials.
