“…Researchers working in this field did not find a common ground on this issue: hypotheses are being discussed such as local melting of materials in the transition zone with their subsequent mixing; severe plastic deformation of the boundary layers; the formation of new phases, etc. Apparently, the lack of consensus on structural changes in the transition zone is associated with the physical and mechanical properties of the materials being joined, their dimensions (thickness) and processing parameters [2][3][4].…”