Special Features of Growth of Intermetallic Phases during Annealing of Nickel-Aluminum Composites

Layered metallic-intermetallic composites formed by explosion welding of nickel and aluminum plates and subsequent annealing of the bimetal for 1 – 100 h at 550, 570, 590 and 610°C are studied. X-ray diffraction analysis is used to determine special features of the structure of interfaces of bimetallic billets after welding and to estimate their contribution into the processes of nucleation and growth of layers of nickel aluminide. It is shown that the formation of the intermetallic is determined primarily by volume diffusion. The activation energy of the growth of the nickel aluminide layer depends on the structural state of the diffusion pair and on the presence of oxide films on the interfaces of the metallic plates.