Structural Properties of Interfacial Layers in Tantalum to Stainless Steel Clad with Copper Interlayer Produced by Explosive Welding

Abstract

A systematic study of explosively welded tantalum and 304 L stainless steel clad with M1E copper interlayer was carried out to characterize the microstructure and mechanical properties of interfacial layers. Microstructures were examined using transmission and scanning (SEM) electron microscopy, whereas mechanical properties were evaluated using microhardness measurements and a bending test. The macroscale analyses showed that both interfaces between joined sheets were deformed to a wave-shape with solidified melt zones located preferentially at the crest of the wave and in the wave vortexes. The microscopic analyses showed that the solidified melt zones are composed of nano-/micro-crystalline phases of different chemical composition, incorporating elements from the joined sheets. SEM/electron backscattered diffraction (EBSD) measurements revealed the microstructure of layers of parent sheets that undergo severe plastic deformation causing refinement of the initial grains. It has been established that severely deformed areas can undergo recovery and recrystallization already during clad processing. This leads to the formation of new stress-free grains. The microhardness of welded sheets increases significantly as the joining interface is approaching excluding the volumes directly adhering to large melted zones, where a noticeable drop of microhardness, due to recrystallization, is observed. On lateral bending the integrity of the all clad components is conserved.

Impact Welding of Materials

“…Paul et al [3] studied the microstructural and mechanical properties of tantalum/copper/stainless steel explosion-welded composites. An exhaustive experimental work, in which several characterisation techniques were used, such as scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, electron backscatter diffraction, microhardness testing, and bending testing, was conducted to characterise the tantalum/copper and the copper/stainless steel interfaces.…”

Corrosion Behavior of Copper Bearing Steels and the Derived In-Situ Coating

“…Steel/copper clad metals are widely studied because they have applications ranging from functional coatings in the electrical and electronics industries, to adhesion promoting coatings, intermediate coatings for improving brightness and leveling effects in decorative/corrosion-protective coating systems, and purely decorative uses as a top coating [3,4]. Electroplating and electroless plating [2,5], cladding [6,7], cold sprayed coating [8][9][10], and casting [11] approaches have been widely used to produce copper-clad steel. Composite materials are more difficult to produce than single materials because of the diversity of their material properties.…”

Interfacial Reactions in the Bonding Zones of Explosively Welded Tantalum to Stainless Steel Sheets

“…[1] To solve these problems, soft and high thermal conductivity copper (Cu) sheet, as an intermediate layer, can be used. [15][16][17][18][19] According to equilibrium binary phase diagrams of Cu-Ta [20] and Cu-Fe, [21,22] for both pairs, the metals are soluble in each other above the liquidus temperatures. However, between liquidus and solidus lines, a miscibility gap exists in these systems.…”

“…Only a few works provide information about manufacturing procedure [1,8] or the influence of EXW conditions on the bond strength and structure of the interfacial layers. [4,[6][7][8][15][16][17][23][24][25][26][27][28] They refer to: Ta/CS, [1,4] Ta/Cu, [16,17,[24][25][26][27][28] Ta/Al, [28] and Ta/SS. [8,15,17] Among them only Paul et al, [7,15,24] Bataev et al, [6] Yang et al, [8] Lysak et al, [23] and Greenberg et al [28] used scanning (SEM) and/or transmission (TEM) electron microscopy analyses to characterize the structure of melted regions.…”

“…[4,[6][7][8][15][16][17][23][24][25][26][27][28] They refer to: Ta/CS, [1,4] Ta/Cu, [16,17,[24][25][26][27][28] Ta/Al, [28] and Ta/SS. [8,15,17] Among them only Paul et al, [7,15,24] Bataev et al, [6] Yang et al, [8] Lysak et al, [23] and Greenberg et al [28] used scanning (SEM) and/or transmission (TEM) electron microscopy analyses to characterize the structure of melted regions. To our best knowledge, there have been no reports concerning in detail the microstructure, phase, and chemical compositions of the reaction regions in copper to steel clads, despite strong interest in Cu/SS composites, e.g., the studies by Zhang et al, Durgutlu et al, and Zhang et al [25,29,30] In this article, a detailed characterization of microstructure, crystal structure, and chemical composition of the reaction regions of EXW Ta/SS and Ta/Cu/SS clads is shown.…”