Effect of Ni Addition on the Interfacial Strength of Al/Cu Dissimilar Welds Produced by Friction Stir Lap Welding

In this study, the bonding of a CuW/Al composite with a Ni interlayer was designed and established by vacuum hot-pressing diffusion bonding. The interfacial microstructure was systematically discussed based on experimental characterization and first-principles calculations. The result indicated that the interface consisted of intermetallic compounds (IMCs) of Al3Ni2 and a few of Al3Ni. The interfacial microstructure significantly differed from the interface without the Ni interlayer. The growth kinetics of the Al3Ni2 layer followed a parabolic behavior, which was mainly affected by the volume diffusion mechanism. The interfacial thickness decreased significantly, and the average thickness was ~35 μm. The microstructural evolution revealed that Al3Ni2 was the phase that was formed first. By introducing a Ni interlayer, the interfacial strength was significantly enhanced due to the IMCs that were changed from Al–Cu and Al–W IMCs to Al–Ni IMCs. The maximum shear strength reached 90.9 MPa, which was increased by 76% compared to that of the sample without the Ni interlayer. An analysis of the fracture morphology analysis showed that the crack was prone to exist at the Al3Ni2/Ni interface and presented a cleavage fracture characteristic.

Section: Introductionmentioning

confidence: 99%

Investigation on Interface of CuW/Al Composite Using Ni Interlayer by Vacuum Hot-Pressing Diffusion Bonding

Wang

Chen

Shao

2023

“…The loss of carbon during the dissolution of tungsten carbide further increases the risk of joint embrittlement [29,30]. In addition, bond phase (cobalt) weakening [31] and interface weakening [32,33] are also important factors causing structural failure.…”

Section: Introductionmentioning

confidence: 99%

Effect of Brazing Filler Metals and Welding Parameters on Laser Welding-Brazing Joints of WC-Co to S1045

et al. 2022

Laser welding-brazing was used to join cemented carbide WC-Co and steel dissimilar materials. In this study, high-speed welding was adopted. The effect of welding parameters and brazing filler metals on the macrostructure, elemental diffusion, micro hardness and thermomechanical behavior was analyzed using optical metallography, scanning electron microscopy, electron probe micro-analysis, hardness test, and finite element method (FEM) based on thermo-elastic-plastic analysis. The experimental results show that increasing laser power is helpful to the increase of maximum welding speed. However, FEM also shows that increased welding speed leads to residual stress concentration, especial in the vicinity of jig. It is still a challenge to optimize laser power welding speed for a given brazing filler metal. The results show: when using pure copper, silver and nickel (thickness is less than 0.5 mm) as brazing filler metal, the combination, laser power of 1.2 kW and welding speed at 0.1 m/s, leads to complete penetration with good weld formation. However, when using Cu/Invar/Ni as brazing filler metal, laser power should increase to 1.7 kW if we still using a higher welding speed (0.1 m/s). Although a trial of high speed welding in laser welding-brazing exhibits feasibility, as-welded joints still have much more brittle risks due to the higher residual stresses.

“…The joining of aluminum to copper has been attractive in electric or battery parts, and it has been investigated [3][4][5]. Further, the addition of Ni at the interface and the coating of the titanium layer on the copper side increased the strength [6,7]. Friction stir "spot" welding technique is also applied to the joining of aluminum, copper and other metals, where the rotating tool stays [8,9].…”

Section: Introductionmentioning

confidence: 99%

Impact Joining of Pure Copper C1100 and Aluminum Alloy A6061-T6 Plates at Edges

Yamashita

Iwatsuka

Taguchi

et al. 2022

Joining of pure copper C1100 and aluminum alloy A6061-T6 plates of 5 mm thickness was investigated. The method was developed by one of the authors, in which the newly created surfaces of a pair of plates obtained by high-speed shear were immediately in contact with a sliding motion with a small overlap length. The total processing time was just about a few milliseconds. To create the new surface, high-speed shaving was also tested. The joining was not possible for the full thickness of the plates. A sharp notch was observed at the joint boundary due to a large shear droop in the copper. Shaving decreased the shear droop, and the joint length through the plate thickness became longer. The joining performance was evaluated by a uniaxial tensile test. The joint efficiency reached 100% using the specimen cut out from the really joined boundary. The affected zone of joining was confirmed by the hardness distribution near the boundary. It was about 30% of the thickness of the plate, which was much smaller than that in welding by heat, and no softened zone was found in both materials.