Abstract:Transient liquid phase bonding of graphite to Ti6Al4V alloy has been conducted with Cu foil, Ti/Cu and Cu/Ti/Cu foils, respectively. A diffusion zone containing Ti-based solid solution and Ti 2 Cu develops between the bonding zone and Ti6Al4V substrate for all the joints. The bonding zones of joints with Cu foil and Cu/Ti/Cu foils are both composed of TiCu and Ti 2 Cu. However, the bonding zone of joint with Ti/Cu foils consists of zones I, II and III. Both zones I and III are mainly comprised of TiCu and Ti 2… Show more
“…The thickness of the joining region (80–85 µm) is lower than those of Ti/Cu foils (100 µm), which may be caused by the liquid filler infiltration into the graphite and spillage of the eutectic liquid phase as well as the consumption of interfacial reaction between the graphite and the Ti-Cu liquid filler. Jiang et al [7] also reported the thickness decrease of the joining region in graphite/Ti6Al4V bonding with Cu/Ti foils, which was caused by the infiltration of Cu-Ti eutectic liquid phase into the graphite. Figure 1 Micrograph (a) and EDX elemental distributions (b–e) of the graphite/Mo joint using Ti/Cu foils.…”
Section: Resultsmentioning
confidence: 99%
“…The result showed that the Ni foil introduction could alleviate the joint stress, thus contributing to the promotion of the joint strength. Jiang et al [7] introduced metal foils including Cu, Cu/Ti and Cu/Ti/Cu foils in graphite/Ti6Al4V alloy TLPB. The joint with Cu/Ti/Cu foils showed the most satisfactory interfacial bonding, thus exhibiting the highest shear strength.…”
Graphite/Mo joining has been carried out using Ti/Cu or Ti/Cu/Nb/Ti/Cu foils. The joining region in the joint using Ti/Cu foils is mainly composed of Ti 3 Cu 4 and TiCu. The joining region using Ti/Cu/Nb/Ti/Cu foils contains a joining zone I, an Nb interlayer and a joining zone II. Both the joining zones I and II are made up of Ti 3 Cu 4 and TiCu. The Nb foil diffuses and dissolves into the liquid fillers during the bonding. The joint using Ti/Cu/Nb/Ti/Cu foils shows higher shear strength than that using Ti/Cu foils, implying the contribution of Nb foil to the joint stress relief and to the joint strength promotion.
“…The thickness of the joining region (80–85 µm) is lower than those of Ti/Cu foils (100 µm), which may be caused by the liquid filler infiltration into the graphite and spillage of the eutectic liquid phase as well as the consumption of interfacial reaction between the graphite and the Ti-Cu liquid filler. Jiang et al [7] also reported the thickness decrease of the joining region in graphite/Ti6Al4V bonding with Cu/Ti foils, which was caused by the infiltration of Cu-Ti eutectic liquid phase into the graphite. Figure 1 Micrograph (a) and EDX elemental distributions (b–e) of the graphite/Mo joint using Ti/Cu foils.…”
Section: Resultsmentioning
confidence: 99%
“…The result showed that the Ni foil introduction could alleviate the joint stress, thus contributing to the promotion of the joint strength. Jiang et al [7] introduced metal foils including Cu, Cu/Ti and Cu/Ti/Cu foils in graphite/Ti6Al4V alloy TLPB. The joint with Cu/Ti/Cu foils showed the most satisfactory interfacial bonding, thus exhibiting the highest shear strength.…”
Graphite/Mo joining has been carried out using Ti/Cu or Ti/Cu/Nb/Ti/Cu foils. The joining region in the joint using Ti/Cu foils is mainly composed of Ti 3 Cu 4 and TiCu. The joining region using Ti/Cu/Nb/Ti/Cu foils contains a joining zone I, an Nb interlayer and a joining zone II. Both the joining zones I and II are made up of Ti 3 Cu 4 and TiCu. The Nb foil diffuses and dissolves into the liquid fillers during the bonding. The joint using Ti/Cu/Nb/Ti/Cu foils shows higher shear strength than that using Ti/Cu foils, implying the contribution of Nb foil to the joint stress relief and to the joint strength promotion.
“…In our previous study, graphite/Cu brazing was also achieved with Cu-TiH2 based fillers [5,6]. Furthermore, transient liquid phase bonding (TLPB), based on formation of liquid phase by the eutectic reaction between metal foils or between metal foil and metal substrate, is an alternative technique for joining dissimilar materials [7]. Ti metal foil has been used to create a good bond between graphite and Cu by TLPB due to the formation of a eutectic phase between the Ti foil and Cu substrate [8].…”
Graphite/Cu bonding is essential for the fabrication of graphite-based plasma-facing parts and graphite-type commutators. Transient liquid phase bonding of graphite/Cu has been conducted separately with Ti/Cu/Ti and Ti/Cu/Ni/Ti multi-foils. The interfacial microstructure and mechanical properties of the bonded joints have been characterized. For the joint with Ti/Cu/Ti multi-foils, complete melting of the Ti/Cu/Ti multi-foils and interdiffusion between the molten zone and the Cu substrate occur during the bonding process, leading to formation of Ti-Cu intermetallics in the bonding area. The liquid phase flowing towards sidewall of the Cu substrate gives rise to a thickness of the bonding area far less than those of the as-received multi-foils. For the joint with Ti/Cu/Ni/Ti multi-foils, the bonding area can be divided into three parts (areas I, II and III). The bonding areas I and III are comprised of Ti-Cu intermetallics and Ti(CuxNi1-x)2, while the bonding area II consists of a Ni layer and two thin TiNi3 reaction layers. The thickness of the whole bonding area is similar to those of the as-received multi-foils, indicating that addition of Ni foil can prevent the loss of liquid phase zone by inhibiting the excessive liquid phase formation. The addition of a Ni foil in bonding of the graphite/Cu may alleviate the joint residual stress by its intermediate coefficient of thermal expansion (CTE) to accommodate any thermal mismatch in the joint and by its superior ductility and plasticity, thus resulting in shear strength promotion of the joint with the Ti/Cu/Ni/Ti multi-foils by approximately 35% when compared to the Ti/Cu/Ti multi-foils.
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