Growth Kinetics of Ni3Ga7 in Ni/Ga System During Interfacial Reaction Diffusion

In order to apply Ga alloys to flexible and wearable electronic devices, it is crucial to verify the mechanical reliability of interconnections between Ga and various metal electrodes. This study investigated the phase transformation kinetics and microstructural evolution in the Ni/Ga couple. The diffusion reaction behavior between nickel and gallium was characterized from 323 K to 623 K for different annealing times. At temperatures lower than 323 K, no obvious intermetallic compound was identified after annealing, according to SEM observation. For reactions at temperatures higher than 423 K, the Ni3Ga7 phase was identified as the only reaction product formed, occurring in a planar morphology along the Ni/Ga interface. The activation energy for the growth of Ni3Ga7 was determined as 58.58 kJ/mol. The kinetic equation expressing the relationship between the thickness of interfacial intermetallic compound, annealing temperature, and time, is the following: d=417174.55exp⁡−58579RTt2.04−0.0024T.