Study On Microstructure Regulation And Deformation Behavior Of Cu-Nb Layered Composite

The development of modern materials science and the application of industrial technology have put forward higher requirements for the strengthening and toughening of metal structural materials,while traditional material strengthening methods often lead to a reduction in their plasticity while increasing the strength of the material.Strength and plasticity are usually The relationship is upside down.The layered configuration design can combine the excellent performance of each component phase,achieve a good match between strength and plasticity,and show excellent comprehensive mechanical properties.In order to study the influence of layer thickness structure parameters on the mechanical properties and deformation behavior of metal layered composite materials,this paper uses vacuum hot pressing,rolling and other methods to prepare Cu-Nb layered composite materials with different layer thickness systems,using optical microscope(OM),scanning electron microscope(SEM),energy dispersive spectrometer(EDS)and other analysis and testing methods to characterize the microstructure of the material,through the room temperature tensile test for mechanical properties test,analysis of layer thickness on the mechanical properties of layered composites To analyze and characterize the influence of layered structural parameters on the dislocation distribution in the material during the deformation process by using white light Laue microdiffraction technology,analyze the mechanism of material micro-domain deformation,and explore the reasons for the layered configuration to achieve the toughening and toughening of the composite material.In this subject,two groups of Cu-Nb layered composite materials with equal layer thickness ratio and different layer thickness were prepared by two different processes of vacuum hot pressing,hot pressing and rolling compound.The material systems prepared by the vacuum hot pressing process are A100,A80,A50 and A30 respectively.The interface of each system is relatively straight,there is no obvious interface gap or crack,and a good combination between Cu and Nb is obtained,and a solid solution layer with a thickness of about 2 ?m is formed at the interface.Through room temperature tensile tests,the room temperature tensile properties of Cu-Nb layered composite plates with different layer thickness systems were tested,and it was found that with the increase of the thickness of the single layer,the uniform elongation and elongation at break of the composite gradually increased,while the material The yield strength and tensile strength of the steel show a trend of decreasing first and then increasing.The composite materials prepared by the method of hot pressing and rolling composite are respectively five systems of 70-70,50-50,20-20,12-12 and 5-5.With the increase of the rolling pass,that is,the rolling reduction,the 70-70,50-50 system layers are relatively smooth,the 20-20,12-12,5-5 systems have shear bands,and a small part of the interface fluctuations are more Large,this is due to the different work hardening ability of Cu and Nb,resulting in a difference in the thickness of the two layers.As the thickness of the single layer increases,the uniform elongation of the composite material shows a tendency to decrease slightly and then increase,while the tensile strength and yield strength of the material show a tendency to increase first and then decrease.Using the ABAQUS simulation software,a single layer of Cu-Nb layered composites with different thicknesses was subjected to tensile simulation.It was found that the stress distribution in the two layers of the different system materials was uneven,and the stress in the Nb layer was greater than that in the Cu layer.The dislocation distribution of Cu-Nb layered composites based on the white beam Laue microdiffraction experiment shows that there are unevenly distributed dislocations inside the prepared material,which are higher at the grain boundaries,inside the grains,and at the layered interface.Dislocation density.The dislocation of the gradient distribution at the interface indicates that there is a certain residual stress at the interface between the initial materials Cu and Nb due to the difference in thermal expansion coefficient and mechanical properties.Through the analysis of the evolution of Laue diffraction peak at different positions under a certain amount of plastic deformation,it is found that the evolution of the layer near the upper and lower interfaces and inside the layer are different,and the analysis has different deformation methods.Therefore,it can be seen that the layered configuration does affect the internal stress state of the material,which in turn affects the dislocation slip mechanism of the material and affects the distribution of strain.The strengthening and toughening of the material is the combined effect of the initial internal stress and the limiting effect of the layered structure,and the change in layer thickness affects the initial internal stress level inside the material,thus affecting the mechanical properties of the material.