Research On Interface Regulation Of Metal Materials And Its Influence Mechanism On Properties

Materials are the essential material foundation for human production and life,and the use of metal materials has a history of more than 3000 years.The reserves of metal materials are large and there are many usage scenarios.Developing high-performance metal materials is a key support for enhancing national competitiveness,especially in high-tech engineering fields such as aerospace and energy materials.Metal materials,whether used in structural or functional materials,have a significant impact on their performance due to their interface.It controls a range of properties,such as hardness,strength,corrosion resistance,and catalytic performance.The particularity of interfaces has aroused great interest in science.This article selects three typical metal materials,namely low-carbon steel,magnesium alloy,and silver nanoparticles,as the research objects.The grain boundaries,twin boundaries,and multiphase interface structures are respectively controlled.Different control processes are selected for different interfaces to improve the performance related to the interfaces.The impact mechanism of interfaces on performance is systematically studied,and the main content is as follows:A quenched low-carbon steel plate with a body centered cubic structure（0.14%C）was rolled at room temperature and subjected to conventional medium temperature annealing to prepare a low-carbon steel plate with a thin pancake shaped nanocrystalline structure.Unlike polycrystalline metal materials,this steel plate contains a large number of small angle grain boundaries,where dislocations merge during stretching,resulting in a decrease in dislocation density.In addition,it was found that subgrain boundaries in steel decompose into lattice dislocations under normal and shear stresses,which not only reduces the orientation difference between adjacent grains,but also reduces the number of subgrain boundaries.The decrease in dislocation density and subgrain boundary decomposition have led to processing softening of pancake shaped nanocrystalline low-carbon steel plates.Low carbon steel（0.14%C）rolled at room temperature is subjected to different elastic stresses during annealing,and the microstructure of the sample is characterized and mechanical properties are tested.Research has found that after annealing at 80MPa-550℃,the average grain diameter is 0.6μm.Compared with the conventional annealing samples at 550℃,the number of grain boundaries decreased by 79%,and the hardness,tensile strength,and yield strength reached 237 HV,795 MPa,and 712 MPa,respectively.Compared with the conventional annealing samples at the same temperature,the hardness,tensile strength,and yield strength increased by 46.3%,44.3%,and 65.9%,respectively.The results indicate that the stress applied during annealing promotes the disappearance of subgrain boundaries and accelerates the formation of high angle grain boundaries;On the other hand,stress also promotes the precipitation of carbides at grain boundaries,and the obstruction of carbides to grain boundary migration inhibits grain growth.The increase in the number of grain boundaries significantly improves the mechanical properties of the material.Increasing the carbon content of quenched low-carbon steel（0.19%C）,after room temperature rolling and hot deformation treatment,it was found that in the 650℃-70.2%hot deformation sample,nanoscale carbides and ultrafine grain ferrite structures were formed,with an average grain diameter of 2.5μm.The number of grain boundaries has significantly increased compared to conventional annealing.Hot deformation above700℃results in the disappearance of carbides and the presence of ferrite grain boundaries and twin martensite twin boundaries within the structure,with a twin boundary spacing of11 nm.After hot deformation treatment at 730℃,the proportion of twinned martensite grains in the structure reached 43%,and the sample hardness was 261.8 HV.The results indicate that increasing the degree of thermal deformation can promote the nucleation of recrystallized grains and increase the number of grain boundaries.As the hot deformation temperature increases,carbides dissolve in the structure,leading to the formation of twin interfaces.Multi interface structures can significantly improve the mechanical properties of materials.High temperature and high pressure treatment of Mg-Li alloy resulted in the formation of coherent compression twin（CTW）interfaces with lithium cluster segregation in the alloy.Lithium rich clusters can prevent dislocations from sliding along the CTW interface and significantly increase the critical shear strain of the CTW interface.After adding Y element to Mg-Li alloy and undergoing high-pressure treatment,a dense composite oxide film was formed at the contact interface between the corrosion solution and the magnesium alloy after soaking in Na Cl solution for 200 hours,which prevented further corrosion of the Na Cl solution.The corrosion rate was only～0.47 mm/y.The theoretical calculation results indicate that the growth ability of lithium clusters follows the following order:CTW>Mg matrix>stacking faults.The lithium cluster segregation twin interface formed by high-temperature and high-pressure treatment is a potential method for achieving excellent performance.The silver nanoparticles were loaded on ZIF-8 by chemical method and then subjected to high-temperature pyrolysis at 900℃.The morphology of the sample was characterized,and it was found that the surface of the silver particles was coated with N-doped carbon shells,forming a N-doped carbon-silver multiphase interface.The electrochemical performance and zinc air battery performance of the sample were tested,and it was found that the sample has high electrocatalytic activity,excellent oxygen reduction performance,half wave potential of 0.83 V,limit current density of 7.03m A·cm^-2,and excellent stability and methanol resistance in alkaline media.Theoretical calculations indicate that the synergistic effect of nitrogen and carbon vacancies can enhance the interaction between silver nanoparticles and N-doped carbon carriers,effectively preventing the migration and aggregation of nanoparticles.Excellent catalytic performance is attributed to high specific surface area and high active N content at the interface.