Preparation And Properties Of W-TiC-Y₂O₃ Composites For Plasma Facing Material

Tungsten is considered as the most promising plasma facing material in ITER because of its advantages,such as high melting point,high thermal conductivity,and low sputtering rate.However,there are some problems of W such as low temperature brittleness,recrystallization brittleness,irradiation damage and damage caused by heat load,which can limit its practical application.The addition of second phase particles in tungsten,such as TiC and Y₂O₃,can improve the mechanical properties of tungsten at room temperature and high temperature.In this paper,TiC and Y₂O₃ doped tungsten composites were prepared by wet-chemical method,and the properties of the sintered composites were tested.Then,the damage behavior of W-TiC-Y₂O₃ composites was studied by laser thermal shock and helium ion irradiation under certain conditions,and the effect of thermal shock on radiation damage was also analyzed.In the end,ultrafine grained W-TiC-Y₂O₃ composites were prepared by spark plasma sintering,and the sintering behavior of the ultrafine powders prepared by mechanical alloying and thermal mechanical method was compared.The thermal shock and radiation damage behavior of composite materials with different grain sizes were investigated and the effect of grain refinement on the properties of the composites was explored.The main results are as follows:?1?The W-TiC-Y₂O₃ composites with a density of 98.85%were prepared by wet-chemical method combined with traditional sintering.The second phase dispersed uniformly on the tungsten matrix,and the grain size of the composites was 30-50?m.Compared with pure tungsten,the thermal conductivity of composite did not decrease significantly and the thermal conductivity was 148.38 W/m·K at room temperature.?2?After helium ion irradiation,a large number of fuzz structures have been formed on the surface of the composite.The crack network is formed on the surface of the sample under the laser thermal shock with different power densities and the laser thermal shock with high power density lead to the tungsten resolidification on the surface of the sample.The samples after thermal shock are irradiated by helium ions.Compared with other damage areas,the central position of the primary thermal shock damage area did not form the fuzz structure.?3?The ultrafine grained W-TiC-Y₂O₃ composites with high density were prepared by spark plasma sintering.The grain size and micro-hardness of the composites were200-500 nm and 869.59 HV,respectively.Compared with coarse-grained W-TiC-Y₂O₃composites,the thermal shock resistance of ultrafine grained composites is not improved,and denser fuzz structure is formed on the surface of ultrafine grained composites under the same condition of helium ion irradiation.