Joining of Graphite to Ti6Al4V Alloy Using Cu‐Based Fillers

Duan, Yu; Mao, Yangwu; Xu, Zhemi; Deng, Quanrong; Wang, Geming; Wang, Shenggao

doi:10.1002/adem.201900719

Cited by 8 publications

(12 citation statements)

References 42 publications

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“…Gao et al claimed that Cu and Ni can replace each other to react with Ti, forming Ti 2 (Cu, Ni) or Ti(Cu, Ni) phases in Cu-Ti-Ni ternary environment. [29] The identification of Ti 2 (Cu, Ni) and Ti(Cu, Ni) was also confirmed by Duan et al [18] Notably, elements V and Al are detected in the filler layers. As claimed by Qin et al and Wang et al, Ti-Al and Ti-V compounds would be formed with Al content higher than 1 1 at% and V content higher than 34 wt%, respectively.…”

Section: Joint Microstructure With Nb Interlayermentioning

confidence: 53%

“…In our previous study, graphite/TC4 brazing has been achieved with Cu-Ti-Ni filler. [18] As reported by Martienssen and Warlimont, the CTE values of Nb and Ta were 7.0 Â 10 À6 and 6.5 Â 10 À6 K À1 , respectively. [19] Considering that refractory metal such as Nb and Ta exhibits a high ductility and an intermediate CTE between those of graphite and TC4, the introduction of a refractory metal interlayer is expected to relax the joint stress by accommodating CTE mismatch between graphite and TC4.…”

Section: Introductionmentioning

confidence: 61%

“…The detailed descriptions of both the substrates and filler had been reported in our previous study. [18] Nb and Ta foils (both with a thickness of 50 μm and a purity of 99.96 wt%), supplied by Qinghe Guantai Metal Materials Co., Ltd., China, underwent surface polishing and subsequent supersonic cleaning in ethanol for 30 min.…”

Section: Methodsmentioning

confidence: 99%

“…In addition, a %20 μm thick diffusion layer is developed close to TC4 due to the interdiffusions of Cu, Ti, and Ni between the liquid filler and TC4, similar to that in the graphite/TC4 joint brazed with Cu-TiH 2 -Ni filler. [18] Fan et al also illustrated the diffusion layer formation near TC4 part in C f -SiC/TC4 brazing with TiCuZrNiþTiC composite filler. [23] EDS elemental distributions (Figure 3b-g) of the interfacial area indicate that the filler layers I and II mainly contain Ti and Cu with a small amount of Ni, Nb, and V. The detection of Nb in the filler layers confirms the diffusion and dissolution of the Nb from the interlayer into the filler layers.…”

Section: Joint Microstructure With Nb Interlayermentioning

confidence: 99%

“…Meanwhile, the infiltration can reduce the porosity of graphite substrate, contributing to the improvement of its mechanical property. [18] Figure 4 shows the magnified morphology and elemental distributions of joining area (see solid-line box in Figure 3a) in the joint. Notably, the structure of filler layer I/Nb interface is virtually similar to that of Nb/filler layer II interface (see dashed-line box in Figure 3a).…”

Section: Joint Microstructure With Nb Interlayermentioning

confidence: 99%

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Effect of Nb or Ta Interlayer on Microstructure and Mechanical Properties of Graphite/Ti6Al4V Alloy Joints

Mao

Duan

et al. 2021

Adv Eng Mater

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Graphite/Ti6Al4V (TC4) joining has been conducted with Cu–Ti–Ni filler and refractory metal (Nb or Ta) interlayer. Microstructural characterizations reveal that defect‐free interfaces are obtained among the refractory metal interlayer, fillers, and substrates, suggesting favorable interfacial bonding in the joints. The diffusion and dissolution of Nb or Ta atoms into the molten fillers occur during joining, leading to the formation of (Ti, R) solid solution ([Ti, R]ss, R = Nb, or Ta) in the filler layers and thickness decrease in the interlayer. Two filler layers adjacent to the interlayer primarily consist of Ti–Cu, Ti–Cu–Ni intermetallics, and (Ti, R)ss. A Ti‐rich diffusion layer and a thin TiC‐containing layer exist near TC4 and graphite substrates, respectively. The joints brazed with Nb and Ta interlayers exhibit shear strength of 2 1.0 ± 2.7 MPa and 20.2 ± 3.1 MPa, respectively, both higher than those without interlayer, implying that the introduction of refractory metal interlayer may benefit the joint stress relaxation by its intermediate coefficient of thermal expansion and high ductility. The joint strength with Nb interlayer is slightly higher than that with Ta interlayer, mainly attributed to the relatively lower elastic modules and yield strength of Nb.

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Section: Joint Microstructure With Nb Interlayermentioning

confidence: 53%

Section: Introductionmentioning

confidence: 61%

Section: Methodsmentioning

confidence: 99%

Section: Joint Microstructure With Nb Interlayermentioning

confidence: 99%

Section: Joint Microstructure With Nb Interlayermentioning

confidence: 99%

See 3 more Smart Citations

Effect of Nb or Ta Interlayer on Microstructure and Mechanical Properties of Graphite/Ti6Al4V Alloy Joints

Mao

Duan

et al. 2021

Adv Eng Mater

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Microstructure and Performance of Graphite/Copper Joints by Brazing with Different Interfacial Structures

et al. 2021

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Graphite is expected to be used for plasma-facing materials in fusion applications due to its low density, good wear resistance, and superior thermomechanical properties. [1,2] To dissipate heat in a radiation environment, it is often required to be joined to a metal, such as copper, which has high thermal conductivity. [3,4] Reliable joining technologies, such as brazing, diffusion bonding, and transient liquid phase joining, are essential for the preparation of graphite to copper joints. Among them, brazing is one of the most popular methods. During brazing, the filler metal with good plastic deformation can relieve the residual stress caused by the mismatched expansion coefficient of base metal. [5,6] The wettability of metal on the graphite surface is a critical problem during the brazing process. The poor wettability of graphite has been partly improved by surface modification of graphite and by adding the active element Ti or Cr to the brazes, which has a strong affinity to carbon. [7,8] Brazes, such as AgCuTi, AgCuInTi, NiCrPCu, and amorphous TiZrNiCu, have been selected to join graphite and metal. [9][10][11][12] Zhang et al. [9] prepared graphite and Cu joints by brazing with graphene nanosheet-reinforced AgCuTibased composites; compared with pure AgCuTi interlayers, the shear strength of the graphite and Cu joints increased by 75% when a graphene nanosheet-reinforced AgCuTi-based composite interlayer was used. Among them, CuTi system active fillers have been widely used. TiH 2 took the place of Ti in the active filler due to the easy oxidation of pure Ti powders. Mao et al. [13] successfully brazed carbon materials to copper with Cu50TiH 2 -based fillers (including Cu50TiH 2 filler and Cu50TiH 2 þ C composite filler) at 1223 K and the average shear strength was 10.8 MPa. The braze filler with active elements can effectively enhance the wettability of graphite, to produce better metallurgical bonding between copper and graphite.Moreover, the large thermal residual stresses caused mainly by the coefficient of thermal expansion mismatch between the two materials exist in the graphite/copper joint, which leads to a strong tendency to crack or even fracture during cooling down from the joining temperature. [14] To release the residual thermal stress of the joint, soft metal foil and a special surface structure were used by means of micromachining. Zhang et al. [15] investigated the interfacial shape effect on the mechanical properties of the joint between carbon-fiber-reinforced carbon composite and copper. The average joint strength of the conical interface improves 3.7 times over the common straight interface brazing joint. Shen et al. [16] obtained conical holes on C/C composites by laser micromachining, and the surface treated with TiH 2 power by the slurry technique was brazed to CuCrZr alloys with Cu-3.5Si brazes. These results suggest that the introduction of the interfacial structure can relieve the joint stress and improve the joint strength.In this study, straight and zigzag interfacial structures ...

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Microstructural and Mechanical Characterizations of Mo/W and Mo/Graphite Joints with BNi2 Paste

Xu,

Cai,

Haider

et al. 2023

Adv Eng Mater

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Brazing of Mo to W and to graphite is achieved using BNi2 paste (containing Ni, Cr, Si, and B). For the Mo/W or Mo/graphite joint, the joining area consists of a diffusion area and a brazing area. The diffusion area is composed of MoNi and Mo, which is formed by diffusion of the Mo substrate into the braze during brazing. The brazing area of the Mo/W joint contains Ni(ss) (solid solution), Cr(ss), Ni3B, CrB, and Ni4W, while the brazing area of the Mo/graphite joint mainly comprises Ni(ss), MoNi, Ni3B, and CrB. A continuous chromium carbide layer is formed at the brazing area/graphite interface in the Mo/graphite joint due to the reaction of Cr in the BNi2 braze with the graphite. Nanoindentation measurements of the joints show that the diffusion area exhibits the highest hardness and elastic modulus in the joints. The shear strengths of the Mo/W and Mo/graphite joints are 58.1 ± 16.0 and 13.0 ± 4.0 MPa, respectively. The Mo/W and Mo/graphite joints fracture after the shear tests in the W and graphite sides, respectively, near the joining area, indicating that both fractures are caused by the stress concentration in the corresponding areas.

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Joining of Graphite to Ti6Al4V Alloy Using Cu‐Based Fillers

Cited by 8 publications

References 42 publications

Effect of Nb or Ta Interlayer on Microstructure and Mechanical Properties of Graphite/Ti6Al4V Alloy Joints

Effect of Nb or Ta Interlayer on Microstructure and Mechanical Properties of Graphite/Ti6Al4V Alloy Joints

Microstructure and Performance of Graphite/Copper Joints by Brazing with Different Interfacial Structures

Microstructural and Mechanical Characterizations of Mo/W and Mo/Graphite Joints with BNi2 Paste

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