Inhomogeneities of the interface produced by explosive welding

Abstract

Results of studying structure of the transition zone for a number of joints produced by explosive welding are presented. The joints of dissimilar metals (titanium-orthorhombic titanium aluminide, coppertantalum, and others) have been investigated. The welded pairs of metals differ from each other in mutual sol ubility; moreover, some pairs (copper-tantalum) virtually lack it. The interface was found to be uneven; it contains inhomogeneities, irrespective of whether it is flat or wavy. It is shown that the formation of interfacial protrusions determines the adhesion of materials. A granulating fragmentation has been found near the pro trusions. The role of various processes in explosive welding has been discussed. The formation of protrusions does not depend on whether the metals of a pair have mutual solubility or not. However, this factor affects the structure of zones of local melting. The metals that have mutual solubility form true solutions; in the absence of solubility, these zones represent colloidal solutions. It is shown that sometimes the local melting zones do not present a real danger for the strength of the joint. A hypothesis is proposed that the formation of a wavy surface is possible through the self organization of the previously formed protrusions.

Structure and properties of joints produced by ultrasound-assisted explosive welding

“…In the area of wave formation, crystals are elongated in the direction of metal flow. Their shape and size are determined by fragmentation pro cesses [5][6][7][8]. Near the area of plastically deformed metal, the grain size decreases due to recrystallization and twinning.…”

Structure and Microhardness of Cu‐Ta Joints Produced by Explosive Welding

“…Below we consider in detail a Cu-Ta system characterized by nearly zero mutual solubility of the components in the solid state [ 9 , 10 ] and high structural stability and mechanical strength of the joint at elevated temperature. Wang et al [ 11 ] note the absence of structural transformations and changes in mechanical properties of a sputter-deposited Cu-Ta composite during heating at 900°C for 100 h. Greenberg et al [ 12 , 13 ] have shown that explosive welding of materials with no mutual solubility results in the formation of a heterophase mixture in the joint region with particle sizes of the dispersed phase similar to those of colloids.…”