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In order to investigate the mechanism of thickness debit effect at different stress levels, creep tests of thin-walled Ni-based superalloys were conducted under three test conditions: 220 MPa, 275 MPa and 330 MPa at 980 °C. Results showed that the creep life reduced with the decrease of specimen thickness at 220 MPa and 275 MPa. At 330 MPa, this variation tendency was not so evident. Metallographic observations revealed that the specimen thickness and the external stress level affected the depth of γ' depleted region and the distribution of voids and cracks of the specimen. Thus, a phase-field model and a crack growth model were used to consider the influence of γ' depleted region and crack growth on life, respectively. It was found from the phase-field model that the existence of γ' depleted region led to more considerable plastic strain and equivalent stress in the normal γ/γ' phase region than that in the γ' depleted region. This phenomenon was more evident in the thin specimen at low stress level. At high stress level, the redistribution of the stress field was not so distinct due to the premature plastic deformation in the normal γ/γ' phase region. The crack growth models showed a shorter critical value of the crack length and faster crack propagation in the thin specimen. However, the increased external stress levels would decrease the disparity of cracks propagation between the thin and thick samples. Comprehensive consideration of the phase-field method and the crack growth model revealed the thickness debit effect at different stress levels.

ITER will be used to test tritium breeding module concepts, which will lead to the design of DEMO fusion reactor demonstrating tritium self-sufficiency and the extraction of high grade heat for electricity production. China plans to test the HCCB TBM modules during different operation phases. Related design and R&D activities for each TBM module with the auxiliary system are introduced. The helium-cooled ceramic breeder (HCCB) test blanket module (TBM) is the primary option of the Chinese TBM program. The preliminary conceptual design of CN HCCB TBM has been completed. A modified design to reduce the RAFM material mass to 1.3 ton has been carried out based on the ITER technical requirement. Basic characteristics and main design parameters of CN HCCB TBM are introduced briefly. The mock-up fabrication and component tests for Chinese test blanket module are being developed. Recent status of the components of CN HCCB TBM and fabrication technology development are also reported. The neutron multiplier Be pebbles, tritium breeder Li 4 SiO 4 pebbles, and structure material CLF-1 of ton-class are being prepared in laboratory scale. The fabrication of pebble bed container and experiment of tritium breeder pebble bed will be started soon. The fabrication technology development is proceeding as the large-scale mock-up fabrication enters into the R&D stage and demonstration tests toward TBM testing on ITER test port are being done as scheduled.

The helium-cooled ceramic breeder (HCCB) test blanket module (TBM) is the primary option of the Chinese TBM program. Current progress on the design and R&D for Chinese helium-cooled ceramic breeder TBM (CN HCCB TBM) in China is presented. The main updated design and related R&D of CN HCCB TBM are introduced briefly. The mock-up fabrication and component tests for Chinese test blanket module are being carried out. Recent status of the components and fabrication technology development is also reported. The neutron multiplier Be pebbles, tritium breeder Li4SiO4 pebbles, and structure material CFL-1 are being prepared in the laboratory scale. The fabrication of 1/3 sized mock-up and construction of a He test loop are being carried out. The key technology development is proceeding to the large scale mock-up fabrication and demonstration tests toward on ITER testing.

Current progress on the design and R&D of Chinese helium-cooled solid breeder test blanket module, CN HCSB TBM is presented. The updated design on structural, neutronics, thermal-hydraulics and safety analysis has been completed. In order to accommodate the HCSB TBM ancillary system, the design and necessary R&Ds corresponding sub-systems have being developed. Current status on the development of function materials, structure material and the helium test loop are also presented. The Chinese low-activation ferritic/martensitic steels CLF-1, which is the structural material for the HCSB TBM is being manufactured by industry. The neutron multiplier Be and tritium breeder Li4SiO4 pebbles are being prepared in laboratory scale.

The hot working characteristics of delta phase in the delta-processed Inconel 718 alloy during isothermal compression deformation attemperature of 950 degrees C and strain rate of 0.005 s(-1), were studied by using optical microscope, scanning electron microscope and quantitative X-ray diffraction technique. The results showed that the dissolution of plate-like delta phase and the precipitation of spherical 8 phase particles coexisted during the deformation, and the content of delta phase decreased from 7.05 wt.% to 5.14 wt.%. As a result of deformation breakage and dissolution breakage, the plate-like delta phase was spheroidized and transferred to spherical delta phase particles. In the center with largest strain, the plate-like delta phase disappeared and spherical delta phase appeared in the interior of grains and grain boundaries. (C) 2009 Elsevier Inc. All rights reserved.

Two actively cooled mock-ups with 2 mm thick tungsten armor joined to chromium copper alloy by explosive welding were developed, tested and analyzed in ASIPP of China. The heat load limit of the mock-up is 7 MW/m 2 , and delamination was observed along the W/Cu interface. The mock-ups can withstand the maximum heat flux of 6 MW/m 2 . SEM investigations showed that some cracks and failures appeared in filler materials and at copper/filler interface, but intactness was found at tungsten/filler interface. Numerical simulations indicated that if the distance decreases between the vertex of channel and the interface, the mock-up had the better structure reliability due to the reduction of temperature and stress. Under 4 MW/m 2 heat flux, the mock-up showed good heat transfer capabilities and high joint reliabilities. All these results demonstrate the explosive joining is also an alternative way to realize the W/Cu joint for the plasma facing components.

The beneficial effects of boron addition on microstructure transformations and mechanical properties of γ-TiAl alloys were investigated. Two growth mechanisms of boride (TiB2) in γ-TiAl alloy were confirmed, the curved flaky borides are products of irregular eutectic reaction growing coupled with matrix, while some faceted blocky borides in boron-rich alloy are primary TiB2 phase growing directly in melt. The core of flaky TiB2 is ultra-fine B2 phase and there has an orientation relationship [1210] TiB2//[001]B2, (1010) //(010)B2. In addition to the well-known grain refinement effect, boron addition can suppress the formation of metastable feathery and Widmastätten structure and broadens cooling-rate-range for the formation of fully lamellar structure, consequently, it improves thermal stability of the lamellar structure and accordingly prolongs the creep rupture life significantly. Another beneficial effect of boron addition is that boride can restrain discontinuous coarsening on lamellar grain boundary by pinning action and accelerates recrystallization of γ grain by introducing TiB2/matrix interfaces as nuclear sites during homogeneous treatment at 1150°C. Therefore, compared with boron-free alloy more homogeneous and refined near γ microstructure can be obtained in boron modified alloy.

The morphology and grain orientation of the surface and the cross section of CVD W coating on a single crystal Mo rod with an axial direction of 〈1 1 1〉 have been characterized by SEM and EBSD. An obvious preferred orientation growth has been found in the W coating. About 80% surface area of the W coating is covered by W grains with a normal direction within 10° around 〈1 0 1〉. A strong {1 0 1}〈1 1 1〉 texture has also been observed in the W coating. EBSD studies suggest that a combination of the Mo matrix introducing growth mechanism and the competing growth mechanism should be responsible for the preferred growth and texture formation.

Preliminary design and analysis for China helium-cooled solid breeder (CH HC-SB) test blanket module (TBM) for testing in ITER device have been carried out recently. In this paper, the design description, the performance analysis and the related ancillary systems for CH TBM are given. The key features of the design are based upon the breeder-outside-tube (BOT) concept, on the use of solid breeder ceramic material, of helium as coolant and tritium purge gas, of ferrite–martensite steel as structural material and of beryllium as neutron multiplier. Results show that the proposed TBM concept has the advantages of higher tritium breeding ratio (TBR), simple structure design and engineering feasibility.

The tungsten–rhenium couple was prepared by using glow plasma physical vapor deposition (PVD) on the isotropic fine grained graphite (IG) substrates. Diffusion anneals of the tungsten–rhenium couple were conducted at the temperature from 1100 °C to 1400 °C to investigate the inter-diffusion behaviors. The results showed that the thickness of the inter-diffusion zone increased with increasing annealing temperature. The relationship between the inter-diffusion coefficient and the annealing temperature accorded with the Arrhenius manner. The value of inter-diffusion activation energies was 189 kJ/mole (1.96 eV). The service time of tungsten–rhenium multilayer diffusion barrier was limited by the inter-diffusion for rhenium and tungsten rather than the diffusion of carbon in rhenium.

Since nanocrystalline materials were first proposed by Gleiter et al. and as a result of their attractive properties, nanocrystalline materials of numerous compositions and structures have been prepared by different techniques among which mechanical attrition (MA) is an easy and effective method. In recent years synthesis of nanocrystalline composites, or nanophase composites have been studied extensively. The main methods used to synthesize nanophase composites by MA are mainly alloy power and ceramic powder together to form homogeneously distributed nanocrystalline metal/ceramic composites and milling element powders under atmosphere or medium to form metal/ceramic composites by reaction between elements and medium. Actually MA of immiscible systems may lead to the formation of a nanophase composite if two components can hardly dissolve into each other. In this paper mechanical alloying is studied for the immiscible Pb-Al and Fe-Cu systems.

Determination of the fracture energy of composite laminates has been broadly studied in recent years. The emphasis of this paper is placed on the laminar fracture behaviour of hybrid (G/C) fibre laminates. The experiments have shown that there are three typical stages of laminar fracture during the fracture process, which exhibit the unique features of laminates. The relationships among the energy, crack length and deflection are established to explain the typical test curves of both specimens, while fractography of the fracture surface is shown using SEM.

An energy approach is applied to evaluate the creep damage of uniaxially compressive concrete specimens but accounting for difference in damage between the axial and lateral direction. This is accomplished by relating the stress/strain state of the damaged configuration to a fictitious undamaged one. Effect of stress multiaxiality can be included in the proposed model by defining a Poisson's ratio that depends on time. Provided is an example of plain concrete under uniaxial compression. Damage in concrete by creep in the lateral direction is found to be more than that in the axial direction. In general, the axial creep strain time history agreed well with the experimental data.