Abstract
Research of structure and properties of Cu-Pb-Cu composite interface, obtained by technology of pack rolling of the pair of mutually insoluble metals, was performed using the methods of metallography, micro- and nano-hardness, mechanical tests, energy-dispersion elementary analyses. The work was aimed at the analyses of possible mechanical mechanisms of mass-transfer, determining the hardness of metal joint in conditions of absence of inter-diffusion. It was shown that different intensity of mass transfer of copper and lead takes place through the composite interface, which corresponds to the results obtained on the other system of dissimilar materials—copper-niobium. Qualitative explanation of these patterns was offered on the basis of more intensive plastic flow of fusible compound of the composite in conditions of roll-bond joining.
Highlights
Formation of physical contact and velocity of formation of atomic bonds in the process of pressure welding are mostly depending on the velocity of formation of so called active centers on the joining surfaces [1]
It was shown that different intensity of mass transfer of copper and lead takes place through the composite interface, which corresponds to the results obtained on the other system of dissimilar materials—copper-niobium
It was determined that layering of materials in the result of different deformability takes place only under loads corresponding to the ultimate tensile strength. They constitute 112 - 128 MPa depending on the thickness of lead layer. This indicates on the high shear strength of the interface, which exceeds 5 - 6 times the ultimate stress of the lead under these conditions of deformation (22 - 25 MPa)
Summary
Formation of physical contact and velocity of formation of atomic bonds in the process of pressure welding are mostly depending on the velocity of formation of so called active centers on the joining surfaces [1]. They are formed in the areas of dislocations output on the surface of metals interface, where the atoms can tear from part of their closest neighbors, create steps on the surface and pass into the new position. It was determined that “old” dislocations which were in the material before deformation, do not significantly influence on the process of pressure welding
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