Preparation And Properties Of Rare Earth Oxide And Carbidestrengthened Tungsten Composites

Due to its high melting point,good thermal conductivity and high strength at high temperature,tungsten has become the most promising plasma-facing materials?PFMs?.However,tungsten exists low-temperature brittleness,recrystallization brittleness,irradiation embrittlement and irradiation damage.The addition of second phase particles,such as Y₂O₃ and TiC,can enhance the high temperature and room temperature mechanical properties and radiation resistance of tungsten materials.In this paper,a wet-chemical method combined with spark plasma sintering was used to prepare W-4vol%Y₂O₃ alloy.The optimal reduction process of W-4vol%Y₂O₃ was investigated.And the sintering properties,thermal shock resistance and radiation resistance properties were also studied.Then W-TiC-Y₂O₃ composites were prepared by wet-chemical method.The effect of TiC content on the microstructure and properties of W-TiC-Y₂O₃ composite was investigated.Finally,A new technology,thermomechanical method,of tungsten-based composites preparation was proposed.The thermal shock resistance property and deuterium retention performance of W-12vol%Ti C-4vol%Y₂O₃ composites prepared by thermomechanical method were compared with wet-chemical method.The following conclusions could be drawn:?1?W-4vol%Y₂O₃ composited powder prepared by wet-chemical method was fully reduced in 4 h at 800 ?under a hydrogen flow rate of up to 600 ml/min.And under this reducing condition the composited powder with smallest particle size?200nm?and best homogeneity could be obtained.?2?After thermal shock,the degree of damage to W-4vol%Y₂O₃ composites increased as the laser beam heat flux increases.W and Y₂O₃ on the surface of the material were melted,and the material occurred recrystallization and cracks.After irradiation with helium,the nanoscale fuzz was formed on the surface of W matrix,whereas the surface of Y₂O₃ was only roughened.So Y₂O₃ showed better radiation resistance.?3?With the increase of TiC content,the density and hardness of W-TiC-Y₂O₃ prepared by wet-chemical method were increased and the grain size was refined.Especially the grain size of W-12vol%TiC-4vol%Y₂O₃ was the smallest,about 5?m.And the second phase exists at both the grain boundary and the grain boundary.?4?Compared with wet-chemical method,the W-12vol%TiC-4vol%Y₂O₃composite material prepared by thermomechanical method has higher density,hardness,smaller grain size and higher material strength.According to the micro-composition analysis of the material,a more stable oxide Y₂?Ti₂O₇?and a solid solution?W,Ti?C_1-x were formed.Finally the morphology after laser thermal shock and the deuterium retention data after deuterium ion irradiation were analyzed.The results show that the W-TiC-Y₂O₃ composite material prepared by thermal-mechanical process has better performance of resistance to thermal shock and deuterium ion radiation.