Intermetallic phase formation in diffusion-bonded Cu/Al laminates

Intermetallic phase formation in diffusion-bonded Cu/Al laminates prepared by plasma activated sintering (PAS) was investigated in the temperature range 673–773 K for 10–30 min. Three intermetallic phases, Al4Cu9, AlCu, and Al2Cu, were identified in all the samples. The formation of Al2Cu as the first phase was rationalized on the basis of the effective heat of formation (EHF) model. The thermodynamic driving force for the preferential appearance of Al4Cu9 at the α-Cu(Al)/Al2Cu interface was evaluated. The time and temperature dependences of the growth of the three intermetallic layers were determined, and their apparent activation energies were calculated. The growth kinetic of the layers conformed to the parabolic law, implying that the intermetallic phase formation was volume diffusion-controlled in the temperature range. The apparent activation energies calculated for the growth of the total intermetallic layer, Al4Cu9, AlCu, and Al2Cu layers were about 80.8, 89.8, 84.6, and 71.1 kJ/mol, respectively.