Fusion Welding Metallurgical Bonding Method Of Aluminum-copper Bimetallic Terminals

The core of this joining technology lies in the atomic-level diffusion formed at the interface between two dissimilar metals. In the manufacturing process, bimetallic lugs typically utilizes the instantaneous heat generated by friction welding to compress the aluminum and copper ends under plastic conditions. This physical process is not a simple contact; rather, it converts mechanical energy into thermal energy, causing a rearrangement of the grains at the interface.

Microscopic Evolution of the Interface Transition Layer

The metallurgical bonding during the welding process is mainly manifested in the interpenetration of aluminum and copper atoms under high temperature and pressure. Scanning electron microscopy (SEM) clearly shows that an extremely thin and uniform eutectic structure is formed at the interface due to the heat-affected zone (HAZ).

• Atomic Diffusion Depth: The thickness of the diffusion layer is directly affected by welding pressure and rotation speed.

• Intermetallic Compound Control: Precise adjustment of process parameters at the grain boundary energy at the interface controls the thickness of brittle compounds (such as CuAl2) to the micrometer level.

• Grain Refinement: Large plastic deformation leads to significant grain refinement in the weld zone, improving the overall density of the joint.

Stability Mechanism of Metallurgical Bonding

bi metal cable lug During thermal cycling, the mechanical strength of the bonding point depends on the integrity of the weld interface. The intermolecular forces generated by fusion welding eliminate the micropores that may exist in traditional brazing. This metallurgical layer exhibits a continuous wavy geometry at the microscopic level, increasing the effective contact area between the two materials.

Although aluminum and copper have different coefficients of linear expansion, the transition layer formed by fusion welding possesses a certain strain buffering capacity. This bonding method, through the reconstruction of chemical bonds, achieves a smooth transition of the potential gradient at the microscopic level, thereby fundamentally solving the hidden dangers caused by electrochemical reactions between dissimilar metals.