Ion Irradiation Damage Study Of Fe And Ni-based Metallic Glass

In the magnetic confinement plasma fusion device,the plasma facing materials are bombarded by strong flow particles from the scrape-off layer of edge plasma.Facing the strong irradiation environment,traditional crystal materials tend to crack and peeling.While metallic glasses with the unique long-range disordered structure and numerous free volume which are beneficial to accommodate incident ions,so that they are considered to have better irradiation resistance.Thereinto,Fe and Ni-based metallic glasses are hot candidate materials for application in irradiation environment because of their good glass forming ability,high glass transition temperature and wide super-cooled liquid region.In this paper,the advantages brought by long range disordered structure to metallic glass in irradiation environment and the effects of irradiation parameters,such as ion energy and species,on the irradiation behavior of materials are discussed.The effects of structural differences on irradiation resistance of Fe and Ni-based metallic glasses,tungsten and reduce-activated steel were investigated by irradiation with He ions of same condition.Meanwhile,He ions with low,medium and high-energy were used to irradiate Fe-based metallic glass to analyze the influence of energy on damage behavior of the metallic glass.The damage processes in metallic glasses induced by H or He ions and their joint irradiation were compared and analysed.In first Chapter,the shortcomings of irradiation performance for traditional crystal irradiation-resistant materials,such as tungsten,molybdenum and low-activated steel,are summarized.And the irradiation behaviors of metallic glasses with different components are reviewed.On this basis,the research direction of this paper is extracted:the differences of irradiation damage threshold and mechanism between metallic glass and crystal metal;the comparison of irradiation resistance among metallic glasses with different components;the effects of ion energy,species and joint irradiation on irradiation behavior of metallic glasses.According to the research ideas in Chapter one,the second Chapter introduces the irradiation platform,analysis method,parameters of the instrument and the selected target materials for the irradiation experiment,the cleaning process,as well as the detailed parameters of the irradiation experiment.In Chapter three,the simulation results of irradiation damage calculated by SRIM program are presented.When the energy is 700 eV,the dominated energy loss method of He ion in the materials changes from nuclear energy loss to electron energy loss.This result provides guidance for the selection of energy parameters in the irradiation experiment.The atomic displacement damage caused by 300 keV He ion irradiation in tungsten is less than that in metallic glasses,which provides data support for comparing the irradiation resistance of materials.Meanwhile,the calculation results also show the energy dissipation processes when the ions enter the materials.Most of the energy is used to bring about the excitation and ionization of electrons and lattice vibration,only a small part of energy is used to form the atomic displacement.This result is helpful for a more comprehensive understanding of the interaction process between the ion and the material.The calculated results of damage induced by H and He ions are compared to help us understand the differences of damage mechanism between the two kinds of ions during the irradiation.In the fourth Chapter,the differences of irradiation behavior under 300 keV He ions irradiation among Fe,Ni-based metallic glasses and tungsten,low-activation steel are compared.The evolution process of the microstructure for metallic glasses with the increase of irradiation fluence is given,and the nucleation and growth mechanism of the bubbles are described.It is obtained that the free volume and long-range disordered structure in metallic glasses are helpful to accommodate more incident ions and atomic displacement damage,and the surface damage threshold of metallic glasses is obviously higher than that of tungsten and low-activated steel.The structural irradiation response of three kinds of metallic glasses is also compared,and it is found that the metallic glass with better glass formation ability has better irradiation structural stability,which provides a reference condition for screening irradiated resistant metallic glasses.Chapter five gives the damage behavior of Fe-based metallic glass under He ions irradiation with different energy.It is found that the undulations or waves are formed on the surface under low energy ion irradiation,while high-energy ion irradiation makes the surface crack and peeling.Two kinds of suface evolution mechanism are put forward:surface viscous flow and self-organization growth of sputtering atom deposition occur under the leading mechanism of nuclear energy loss,local jet of pressure wave happened in the electron energy loss mechanism under medium and high energy ions irradiation makes the surface fracture.For He ions irradiation,in the energy range of several hundred keV to several MeV,the ordered arrangement of atoms forms the ?-Mn phase first in the Fe-based metallic glasses.In Chapter six,the damage behaviors of Ni-based metallic glass and tungsten irradiated by H ions were observed.Compared with He ions irradiation,H atoms has a smaller sputtering yield and a lower degree of induced roughness on the surface of metallic glass.Meanwhile,incident of H ions into metallic glass does not form a bubble layer.In addition,the damage caused by He and H ions joint irradiation and single ions irradiation in Fe-based metallic glass are compared.Compared with the case of single ion irradiation,the bubble density increases and the size decreases under the joint irradiation.It is indicated that the bubble formation mechanism transforms to movement and capture.Chapter seven summarizes this research,gives the main conclusions and innovation points,and analyzes the shortcomings of the research,looks into the future work.