Contact Melting Mechanism in the Cu-Ti System

Abstract

A mechanism for the formation of the interaction zone at the interlayer interface of the explosively welded Cu-Ti system composite is proposed and experimentally proved; the heat treatment was performed under a contact melting regime.

Influence of Nickel Content on the Formation of an Interaction Zone during Contact Melting of Titanium with Copper-Nickel Alloys

“…It is a mixture of Ti2Ni(Cu), TiNi(Cu), and Ti2Cu(Ni) intermetallics (Figure 11, Table 12). Changing the region of the eutectic structure formation and its phase composition allowed us to conclude that the CM process was ongoing according to a mechanism similar to that described in [22,24]. Metallographic studies of IZ after heat treatment at 850 • C, 50 h + 950 • C, 1 min showed that on the side of the CuNi45 alloy, interlayers of TiNi 3 (Cu), TiCuNi, TiNi(Cu) and Ti 2 Ni(Cu) were formed, and on the side of titanium VT1-0 solid solution based on αTi was formed (Figure 10, Table 11).…”

“…It is a mixture of Ti 2 Ni(Cu), TiNi(Cu), and Ti 2 Cu(Ni) intermetallics (Figure 11, Table 12). Changing the region of the eutectic structure formation and its phase composition allowed us to conclude that the CM process was ongoing according to a mechanism similar to that described in [22,24]. In accordance with [22,24], an increase in the nickel content in β-Ti to a certain critical concentration led to the "blocking" of its individual small regions by "partitions" of nickel atoms and the formation of nano-sized volumes (clusters) on which size effect of melting was realized [21].…”

“…There are many known methods for producing Ti-Cu coatings: pack cementation [14,15], self-propagating high-temperature synthesis [16], laser processing [17], electrolytic deposition [18], and electric spark alloying [19,20]. The most promising method is one that includes explosive welding followed by heat treatment via contact melting (CM) [21][22][23][24]. Explosive welding makes it possible to obtain plastic metal composites of various dimensions, which can be subjected to pressure treatment in order to give semi-finished products the required shape and size.…”

“…Subsequent heat treatment under contact melting conditions leads to the formation of an interaction zone (IZ) at the joint boundary as a result of reactive diffusion. The formation of the coating is achieved by dissolving one of the metal layers completely in IZ or by mechanically separating the unreacted part [22][23][24]. Using this technology, it is possible to obtain defect-free coatings of various thicknesses, chemical and phase compositions in a short time.…”

“…Contact melting in the Cu-Ti system at the boundary of an explosively welded composite begins above the eutectic L↔TiCu 4 + TiCu 2 at a temperature of about 900 • C [22]. In the Ni-Ti system, contact melting begins above the eutectic L↔βTi + Ti 2 Ni at a temperature of about 970 • C [24].…”