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The aim of this study is to investigate the structure development and growth kinetics of the interfacial structure of cold roll bonded Al/Cu bimetal sheet. An interfacial structure is developed during the annealing process. The characteristics of the constituent phases at the interface of Al/Cu bimetal are studied by means of scanning electron microscope (SEM), X-ray diffraction (XRD) and transmission electron microscope (TEM). The results indicate that an obvious multi-layers interdiffusion structure is developed at the Al/Cu interface. The diffusion layer is consisted of four intermetallic compounds; Al 2 Cu, AlCu, Al 3 Cu 4 and Al 4 Cu 9 . The growth of these intermetallics during annealing can be achieved by the diffusion process. The activation energies of Al 2 Cu, AlCu + Al 3 Cu 4 , Al 4 Cu 9 and the total intermetallic layer are found to be 97.504, 107.46, 117.52 and 107.85 kJ/mol, respectively. These intermetallics generally possess higher hardness values than those of the corresponding base metals. AlCu and Al 3 Cu 4 exhibit much higher hardness than that of Al 2 Cu and Al 4 Cu 9 , which implies lower fracture toughness. The observation of crack propagation paths shows that fracture mainly occurs in the intermetallic compound layers of AlCu and Al 3 Cu 4 , which are located between Al 2 Cu and Al 4 Cu 9 .

The dominant point defects in p-type NiO films were determined by analyzing the coordination number (CN) change with various annealing temperatures and the composition profile of double-layer films deposited individually in oxygen and in argon atmospheres. The results show that the nonstoichiometry of sputtered NiO film is determined by the number of nickel atoms rather than by the number of oxygen atoms. It is concluded that nickel vacancies are the dominant point defects that result in the electrical conductivity of NiO films.

The aim of this article is to study the influence of interfacial structure development at interface on the fracture mechanism and the bond strength of cold roll bonded Al/Cu bimetal plate. The Al/Cu bimetal plates are produced by cold roll bonding and then sintered at different conditions. The bond strength of the Al/Cu bimetal plate increases generally to maximum values and then decreases to low values with increasing sintering temperature and time. Interfacial structures develop with increasing sintering temperature and time. The main interfacial layers are Al 2 Cu, AlCu, Al 3 Cu 4 and Al 4 Cu 9 . The formation and thickening of those intermetallic compounds promotes cracks propagation and weakens the bond strength of the bimetal plates. The fracture mechanism transforms from ductile to brittle cleavage with the development of interfacial structures. While the bond strength of the material starts to decrease, no obvious Kirkendall effect of void formation is observed in the present study.