ABSTRACT
The Zygo NewView 7300 optical profilometer was used to study the surface roughness of the starting materials. The equipment of the Center for Diagnosing Structure and Properties of Materials was also used: an OLYMPUS GX51 optical inverted microscope; scanning electron microscope Quanta 600; ion cannon Fashione 1010 ION MILL. The reason for the insufficient extent of electron microscopic studies of welded joints is the difficulty of making foils from dissimilar materials. In the process of thinning one of the metals can be completely etched, so that the foil remains only from another material. Thus, for a copper–tantalum joint with high corrosion resistance of tantalum, only a special selection of reagents makes it possible to prevent copper etching. The lower boundary of the ‘weldability window’ is important both for practical calculations of welding conditions and for understanding the processes that determine the possibility of the formation of a welded joint.
