Effects Of Components In Equiatomic Alloys On Atomic Diffusion

At present,the research on binary,ternary and quaternary isoatomic alloys at home and abroad has mainly focused on the microstructure and properties,and less research on the atomic diffusion of isoatomic ratio alloys.For solid atomic alloys,the internal diffusion in atoms directly determines the phases stability,and then affects the phase transition in the solid state.Therefore,it is of great significance to study the diffusion of isoatomic ratio alloys under different components,to understand the microstructure of isoatomic ratio alloys,and to promote the application of isoatomic ratio alloys in practical environments.In this thesis,a vacuum arc melting furnace is used to prepare isoatomic ratio alloys.Pure copper is plated on the surfaces of four binary alloys CuCo,CuNi,FeCr,FeNi,four ternary alloys CuCoNi,CoCrNi,FeNiCr,FeCoNi,and two quaternary alloys CoCrCuNi,CoCrFeNi.Forms a diffusion couple of copper with different equiatomic ratio alloys.These diffusion couples were respectively subjected to diffusion annealing treatment under different conditions.The annealing temperature was repectively 850 ℃and 950 ℃,with the holding time 6h and 10 h.The microstructure and composition distribution in the diffusion couple under diffusion annealing are analyzed,and the diffusion behavior of Cu atoms in different types of isoatomic alloys is studied.The experimental results show that the atoms in the three diffusion couples with binary alloys can diffuse and form a diffusion layer with a certain thickness.In the Cu-CuNi alloy diffusion couple,with the increase of the annealing temperature and the extension of the holding time,the thickness of the atomic diffusion layer increases;under the condition of a constant holding temperature,the holding time of the Cu-FeNi alloy diffusion couple is extended.The thickness will decrease.In ternary isoatomic ratio alloys,no interdiffusion occurs.In the CuCoCrNi diffusion couple,Cr atoms in CoCrNi diffuse into the coating,and Cu atoms in the coating do not diffuse.In quaternary isoatomic ratio alloys,Cu atoms are in CuCoCrCuNi.Grain boundary segregation occurs in the diffusion couple;in the CuCoCrFeNi diffusion couple,Cr atoms in CoCrFeNi diffuse into the plating layer,and Cu atoms in the plating layer do not diffuse.In isoatomic ratio alloys,Cu atoms undergo lattice diffusion or grain boundary segregation.In addition to the influence of ionic radius,they are also affected byvacancy formation energy.That is,under certain conditions,the higher the value of the vacancy formation energy in an isoatomic ratio alloy,the smaller the number of vacancies in its lattice,and the less likely it is that atoms will diffuse.