| Metallic glass is characterized of a short range ordered and long range disordered metastable amorphous structure,and keep the structure stable within a certain temperature range.Compared with traditional crystal structure materials,metallic glass has no internal defects such as grain boundaries,dislocations and the like,and contains a large amount of free volume.Metallic glass is likely to be a candidate for radiation resistant materials in fusion devices.However,the thermal stability of metallic glass is the key to its application.The mechanism of thermal irradiation damage is not clear,and it is necessary to study the thermal stability of metallic glass.High-intensity pulsed ion beam?HIPIB?technology has the characteristics of high energy and short pulse,can not only achieve ion beam irradiation effect of fusion device,and can well simulate the effect of transient heat load of fusion device.It is very suitable to study the irradiation damage of material,especially the thermal stability of amorphous materials.In this paper,HIPIB with acceleration voltage of 200-240 kV and the pulse width of 90ns was used to irradiate metallic glass Fe80Si7.43B12.57,Ni62Ta38.And compared tungsten,which is the most promising plasma facing material.Irradiation parameters are divided into two groups:A.the energy density was 0.2-0.3 J/cm2,the times of total pulses were 3,10,100 and300,respectively;B.the number of pulses was 3 times,the energy density were 0.2-0.3 J/cm2,0.8-1.3 J/cm2,1.6-2.5 J/cm2.The changes of surface,structure and properties of metallic glass and tungsten before and after irradiation were analyzed.The structure thermal stability of Fe-and Ni-based metallic glass was studiedX-ray diffraction?XRD?showed that after the HIPIB irradiation of different parameters,Fe80Si7.43B12.57 metallic glass remained amorphous.After irradiation of different pulse times,the surface morphology of metallic glass did not change significantly.Only when the number of impulses was 300,a large number of round holes and a few"bumps"appeared on the surface of Fe-based metallic glass.No obvious irradiation damage was observed on the surface after irradiation with different energy density.High resolution transmission electron microscopy?HRTEM?showed that HIPIB irradiation had a great influence on the near-surface atomic arrangement of Fe-based metallic glass.Irradiation induced strong migration and aggregation of atoms inside the metallic glass,making the atomic arrangement uneven.Despite the local existence of an orderly arrangement of atoms,the metallic glass remained amorphous.After irradiation,the surface reflectance of the metallic glass decreased slightly.Metallic glass Ni62Ta38 remained an amorphous structure after HIPIB irradiation at different impulse frequencies.But the arrangement of atomic structure in the depth of about700nm from the surface of metallic glass became more disordered after irradiation.When the number of pulses increased to 300,a small amount of"bumps"appeared on the surface of the metallic glass,and no radiation damage such as cracks occurred.The formation of“bump”is because of the ion cathode diode due to occasional ablation of cathode during beam formation process.For metallic glass,the number of pulses had more obvious impact on its structure and performance than that of energy density.For crystal material tungsten,the energy density had more obvious impact on its structure and properties than the number of pulses.Fe-and Ni-based metallic glass has good heat radiation resistance and structural thermal stability.This will be a very important reference value for the selection of radiation resistant materials in fusion devices. |
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