Preparation And Irradiation Effects Investigation Of Fine Crystalline W Plasma Facing Materials

Tungsten and tungsten-based composite materials have become one of the mostpromising plasma facing materials due to its high melting point, high thermal conductivity,low vapor pressure and low sputtering yield and low retention properties of hydrogen.However, the properties of current tungsten materials need to be improved since theycannot meet the requirements of nuclear fusion devices.In this research, the fabrication process of ultra-fine grain size pure bulk tungsten andtungsten composites by high energy ball milling and spark plasma sintering is described.The paper focuses on the influence of high energy milling parameters （process controlagents, ball-to-powder weight ratio and milling time） on the microstructure of tungstenpowder, the influence of activated tungsten powder on the density, microstructure andproperties of tungsten bulk material, the principle of how powders sintered to be defined.Also, the influence of addition of different particles （TiC, Y₂O₃, La₂O₃） to matrix tungstenhas been compared. The influence of Ni, Mo on densification of matrix tungsten isinvestigated. Finally, behaviors of resistance to irradiated damage of Tungsten materialshave been compared.The main results are as follows:Pure bulk tungsten material is prepared by high energy ball milling and spark plasmasintering. Under the optimum conditions, the crystalline size of milled powders couldreach to about15nm. The influences of the activated W powders on the relative density,microstructure and properties of bulk tungsten are also investigated. A homogenousdistribution of fine W grains （8μm） is formed by SPS. The relative density of thefabricated material is increased accordingly and the hardness is546HV.The addition of TiC, Y₂O₃, La₂O₃can apparently decrease the grain size of tungstencomposite. For W-10%TiC composite, the average grain size is below1μm, the Vickershardness is1604and the relative density is93.69%. Ni can realize the tungsten lowtemperature sintering （1200°C）, and enhances the material relative density obviously. ForW-5%Ni composite, the relative density is96.17%and the grain size of W could reach toabout1μm. W-10%TiC-5%Ni is prepared by high energy ball milling and spark plasma sintering. For W-10%TiC-5%Ni composite, the relative density is96.56%and the Vickershardness is1398HV.The W-10%TiC-5%Ni material’s anti-irradiation performance is best, after theirradiation, changes are not obviously.