Multi Axial Creep Fatigue Damage Accumulation in Vacuum Brazed Battery Pack Cooling Structures
Vacuum brazed aluminum cooling plates fail under coupled multi-axial creep-fatigue when pressure pulses interact with static cell swelling constraints.
Core Alloy Erosion
Meaning
Dissolving core metal into molten filler material during high-temperature joining processes alters structural geometry and chemical composition. Metallurgists monitor core alloy erosion in aluminum heat exchangers used for battery thermal management systems during controlled atmosphere brazing. Excess brazing temperature or prolonged dwell time causes silicon from the Al-Si filler metal to diffuse inward, melting the supporting substrate.
The boundary of this mechanism ends at the braze joint interface, beyond which solid-state corrosion or bulk mechanical overload dictates structural endurance.
Dissolution Rate
Diffusion of liquid phase elements into solid grain boundaries controls the rate of metal loss. During thermal processing, core alloy erosion accelerates when peak temperatures exceed alloy melting points, causing rapid intergranular penetration. Liquid fillet material dissolves the core wall, weakening structural partitions.
Lowering peak furnace temperatures minimizes phase boundary degradation.
Thickness Degradation
Remaining structural wall thickness dictates maximum internal pressure limits in liquid cooling plates. Uncontrolled core alloy erosion reduces burst pressure capacity by thinning the load-bearing metal skin.
Material Selection
Core composition design counteracts rapid filler diffusion through protective diffusion barrier layers. Selecting core alloy erosion resistant aluminum series with manganese additions elevates solidus temperatures and preserves structural integrity during brazing cycles. Proper alloy matching ensures consistent heat exchanger longevity under thermal cycling conditions.