DO22-(Cu,Ni)(3)Sn intermetallic compound nanolayer formed in Cu/Sn-nanolayer/Ni structures

The present work conducts crystal characterization by High Resolution Transmission Electron Microscopy (HRTEM) on Cu/Sn-nanolayer/Ni sandwich structures associated with the use of Energy Dispersive X-ray (EDX) analysis. The results show that DO22-(Cu,Ni)(3)Sn intermetallic compound (IMC) ordered structure is formed in the sandwich structures at the as-electrodeposited state. The formed DO22-(Cu,Ni)(3)Sn IMC is a homogeneous layer with a thickness about 10 nm. The DO22-(Cu,Ni)(3)Sn IMC nanolayer is stable during annealing at 250 degrees C for 810 min. The formation and stabilization of the metastable DO22-(Cu,Ni)(3)Sn IMC nanolayer are attributed to the less strain energy induced by lattice mismatch between the DO22 IMC and fcc Cu crystals in comparison with that between the equilibrium DO3 IMC and fcc Cu crystals. (C) 2009 Elsevier B.V. All rights reserved.