Joint resistances and current paths in heat-treated aluminium/copper solid-phase welds

Abstract

Results are presented for the changes in resistance of aluminium/copper solid-phase welds caused by intermetallic layer growth at the weld interface. An analogue method is used to show the effect of the intermetallic layers on the current path for welds in which the current does not flow perpendicularly across the joint interface. These analogue studies resolve an apparent discrepancy between values of resistivity of the intermetallic layers measured on two samples of different designs. Thus the value of the electrical resistivity of the overall intermetallic layer in Al/Cu heat-treated solid-phase welds is shown to be ∼ 13 μΩcm. Since the widths of the total intermetallic layer in Al/Cu and similar bimetallic solid-phase welds will be extremely narrow (< 2 μm) in most practical applications, it is concluded that while the resistances of such joints will be dependent on their geometry, properly bonded joints should not contribute significantly to a resistive power loss.