Compatibility between Aluminium Nitride and Nickel

Abstract

In relation to the joining of aluminium nitride ceramics to metal, the reaction products and the reaction mechanism between AlN and Ni have been investigated under a nitrogen or an argon atmosphere at temperatures of 1273-1673K. Using AlN-Ni powder mixtures, reaction rates were determined by thermogravimetric analysis and the reaction products were examined by X-ray diffraction. The reaction between AlN and Ni occurred above 1250K under both N₂ and Ar atmosphere. Under N₂ atmosphere, the reaction product was only a Ni-Al solid solution. Under Ar atmosphere, at higher temperatures and on prolonged heating, the reaction product was changed in the following order: Ni-Al solid solution, Ni-Al (s.s.)+Ni₃Al, Ni₃Al, Ni₃Al+NiAl and finally NiAl. The initial rates of the reaction obeyed a linear rate law. Under both N₂ and Ar atmosphere, the rate constants and the activation energies (224 and 210kJ/mol) showed comparable values. The reaction rate is thought to be controlled by a chemical process, such as the dissociation of AlN. When the Ni particles were covered with a reaciton layer, the rate obeyed a parabolic rate law. The rate constant under N₂ atmosphere was 2 orders of magnitude lower than that under Ar atmosphere. In the range of stability of Ni-Al(s. s.), the activation energy under N₂ atmosphere (124kJ/mol) was almost identical to that under Ar atmosphere (127kJ/mol). Under Ar atmosphere, the activation energy for Ni₃Al formation was 342kJ/mol. The kinetics are probably determined by solid-state diffusion through the reaction layer.