No abstract

Li2TiO3 has been recognized as one of the most promising tritium breeding materials for D-T fusion reactor blanket. In this study, ultra-fine Li2TiO3 powder was prepared rapidly by microwave-induced solution combustion synthesis (MSCS) using nitrates of lithium and titanate as raw materials, citric acid as fuel. The as-synthesized Li2TiO3 powder exhibits an average crystalline size as small as 20 nm with uniform distribution. Computer-assisted 3D printing technology was employed to fabricate Li2TiO3 ceramic breeding pebbles. This computer-assisted process is precise, efficient and controllable, which offers an alternative for the mass production of Li2TiO3 pebbles. The pebbles exhibit good sphericity, relatively small grain size, preferable sinterability and crushing load strength.

Effect of annealing temperature on microstructures and properties of warmly deformed SCRAM (Super-clean Reduced Activation Martensitic) steel on Gleeble-3500 thermo-simulation machine was investigated. The results showed that an increase in the annealing temperature can result in increasing the martensitic lath width from 0.48 um to 0.65 um and decreasing the dislocation density from 6.4×1015m-2to 2.8×1015m-2in SCRAM steel. The specimen exhibited high reduction of area and total elongations when the annealing temperature is up to 600 oC. The tensile fracture surface observation indicated that dimples became more uniform and deeper and cleavage fracture traces disappeared with the annealing temperature increasing. The irradiation-induced helium bubbles and hardening were observed in all the specimens after helium implantation to 1e + 17/cm2at 450 oC. The helium bubbles became larger but less when the annealing temperature increased. The optimal annealing temperature is 450 oC in this experiment.

The martensitic lath width (0.83 ± 0.45μm ∼ 0.48 ± 0.14 μm) and dislocation density (1.3 ± 0.3 × 1015 m−2 ∼ 6.4 ± 1.6 ×1015 m−2) change of Super-clean Reduced Activation Martensitic (SCRAM) steel caused by warm deformation on Gleeble-3500 thermo-simulation machine have been examined. The irradiation-induced helium bubbles and hardening were observed in all the specimens after helium implantation to 1e + 17/cm2 at 723 K. The helium bubbles became smaller and more numerous while the distribution was more homogeneous when the lath width decrease and dislocation density increase. The nano-indentation hardness indicated that the sample, the martensitic lath width is 0.83 ± 0.45μm and the dislocation density is 1.3 ± 0.3 × 1015 m−2, exhibited the maximum nano-indentation variation (ΔH) and the ΔH decreased with the lath width decreasing and dislocation density increasing. The hardening occurred in all helium implanted samples can mainly be ascribed to helium bubbles.

The SCRAM steel was processed by warm deformation on Gleeble-3500 thermo-simulation machine. The effect of strain on the microstructures and mechanical properties of SCRAM steel was investigated. The results show that an increase in the strain can result in refining the martensitic laths, increasing the volume fraction of precipitates and the dislocation density in SCRAM steel. The martensitic lath width decreases from 0.83 μm to 0.48 μm and the dislocation density increases from 1.3 × 1015 m-2 to 6.4 × 1015 m-2 in SCRAM steel. The specimen exhibits high ultimate tensile strength and yield strength but low reduction of area and total elongations when the strain (ε) is up to 0.5. The tensile fracture surface observation indicates that dimples become smaller and shallower while tear ridges drastically grow up with the strain increasing.