Quantifying Galvanic Corrosion Kinetics across Battery Pack Busbar Terminations
Galvanic corrosion kinetics at battery busbar joints depend on potential offsets, area ratios, and moisture film thickness, requiring controlled plating barriers.
CuAl2 Phase
Meaning
An intermetallic compound results from the solid state diffusion between copper and aluminum during welding or thermal aging. The presence of the CuAl2 phase at a joint interface increases the electrical resistance of the connection. Often referred to as theta phase, this structure is hard and lacks the ductility of the parent metals.
Formation occurs primarily when temperatures exceed two hundred degrees Celsius during the assembly process.
Structural Formation
Atomic diffusion drives the growth of this layer at the boundary of the two materials. While the CuAl2 phase provides a metallurgical bond, its thickness must be strictly controlled to prevent failure. Growth rates follow a parabolic law based on time and temperature exposure.
Mechanical Hardness
High brittleness makes the connection susceptible to failure under mechanical shock or thermal expansion. Because the CuAl2 phase has a different crystal structure than the bulk metals, internal stresses develop as the layer expands. Vibrational testing reveals cracks that originate within this intermetallic zone.
Thermal Resistance
Increased heat generation occurs when current passes through an interface dominated by these brittle layers. The CuAl2 phase acts as a barrier to efficient electron flow within the battery busbar system. Thermal imaging identifies hot spots that indicate an excessive accumulation of this compound.
Management of this phase is mandatory for maintaining the efficiency of high power discharge cycles.