Preparation And Properties Of Plasma Facing Rare Earth Oxide Strengthened Tungsten Matrix Composites

Due to their excellent performance, tungsten and its alloys were chosen as the candidate of ITER plasma facing first wall material, but they have low-temperature brittleness, radiation reduced brittleness and high ductile-to-brittle transition temperature, so it can’t reach the requirements as the plasma facing first wall materials needed. Addition of strengthening phases to tungsten alloys is a kind of preparation method to improve combination properties of tungsten alloys. In this paper, novel ODS-W composite samples were fabricated by mechanical ball-milling and spark plasma sintering method from the tungsten powders and lutetium oxide (Lu2O3) nanoparticles. The effects of the contents of Lu2O3 and the technology of mechanical ball-milling on the microstructures and properties of ODS-W composite samples were researched. And the effects of the addition of trace Nb and C on the microstructures and properties of W-Lu2O3 composite were also studied. Moreover, the deuterium retention and heat load performance of the prepared ODS-W composite samples were studied. The following conclusions could be drawn:(1) The relative density and microhardness of the prepared ODS-W composite samples increased with the increase of Lu2O3 content, and highest values were 96.21% and 551.7 HV, respectively, when the content of Lu2O3 particles was 3wt.%. And the grain size of ODS-W samples was decreased while the content of Lu2O3 increased.(2) With the increase of milling time, the grain size of the prepared W-3wt.%Lu2O3 composite powders and sintered samples were decreased, but the relative density and microhardness of the sintered samples showed a small amplitude decrease first and then a trend of increasing, and maximums were 93.83% and 505.1 HV, respectively, when the ball-milling time was 40 h.(3)The addition of trace elements of Nb and C into tungsten on the basis of doped Lu2O3 had a significant effect on the grain refinement, densification and strength improving. The relative density of W-Nb-C-Lu2O3 composite increased by 5.75% and reached 95.12%, the grain size refined from 8～13 μm to 2～5μm, and the microhardness and tensile strength increased by 20% and 45%, respectively, which reached 496.3 HV and 197.2 MPa, respectively.(4) When the D+reached a certain irradiation dose, the amount of deuterium retention of the W-3wt.%Lu2O3 composite was lower than that of W, showed a better performance in deuterium retention. And the W-3wt.%Lu2O3 composite showed a better electron beam heat load resistance in the electron beam heat load experiments. Moreover the W-3wt.%Lu2O3 composite can withstand a 50 MW/m2 power density of laser beam heat load at least.