Annealing effects on the intermetallic compound formation of cold sprayed Ni, Al coatings

The annealing of Ni and Al coatings under various conditions on substrates fabricated by a cold gas dynamic spray process (CDSP) were investigated. The powder particles were accelerated through a standard De Laval-type nozzle with air used as the main carrying gas. The coatings were annealed at 450–550 °C in either argon or air atmospheres for 4 h. In the case of Ni coatings during annealing both in argon and air atmospheres, intermetallic compound layers such as Al3Ni and Al3Ni2 were observed at the interfaces between the Ni coating and Al substrate. Also, the intermetallic layer formation of Al3Ni and Al3Ni2 at the interfaces depended on the solid-state diffusion and the annealing temperature. The intermetallic compound AlNi was obtained at the interface of Al coating on a Ni substrate by low-temperature annealing under the melting temperature.