Study On Damage Behavior Of Plasma Facing W-Nb Composites Under Helium Irradiation

Tungsten has become the most promising plasma-facing materials(PFMs)because of its good thermal conductivity and high strength at high temperature.However,the disadvantages of tungsten including the recrystallization brittleness,low temperature brittleness,irradiation embrittlement limit its application in fusion reactor.A small amount of alloying elements can enhance the comprehensive properties of tungstenbased materials.Firstly,W-Nb composites were prepared by mechanical ball mill and sintered by SPS.The effects of different milling time on radiation resistance of W-Nb composites were studied.And the effects of different irradiation energy and heat treatment temperature on radiation resistance of W-Nb composites were investigated.The following conclusions could be drawn:(1)The different milling time results in the different degree of solid solution of W and Nb in the composites,which leads to the difference of the radiation damage degree.Among them,the sample milled 36 h had the lowest degree of solid solution,and the surface damage was the most serious after irradiation,with fuzz structure appearing on the surface.In addition,in the same sample,different orientations lead to different surface damage morphologies.The surface morphologies of W-rich and Nb-rich regions after irradiation are also quite different.The Nb-rich regions are more damaged and cannot produce nano-fuzz structures.(2)The surface damage morphologies are different under different irradiation energies.The surface morphology of 80 e V helium ion irradiation edge is similar to that of 50 e V helium ion irradiation center,and only swelling appears on the surface.The central region of the sample irradiated by 80 e V helium ion forms fuzz structures,and the Nb-rich region appears larger holes or abscission.(3)With the increase of heat treatment temperature,the fuzz structure of pure tungsten samples after helium ions irradiation gradually degenerates,and disappears completely when the temperature reaches 1300°C.In W-Nb alloys,the surface morphology of W-rich region remained basically unchanged,while the holes in Nb-rich region were repaired with the increase of temperature.