Abstract
In this work, Ni–14Al, Ni–30Al and Ni–58Al alloys representing Ni3Al, NiAl and NiAl3 phases were studied. First of all, they were prepared by reactive sintering to show which phases are present in the obtained microstructure. Subsequently, reactions between nickel and aluminum were observed below and above the melting point of aluminum allowing to propose reaction mechanism and to determine kinetics. Experiments below melting point were carried out as annealing of the powder mixture and phase composition was studied while experiments at higher temperatures used special experimental model consisting bulk nickel and molten aluminum. Results showed that Ni2Al3 phase formed preferentially in all alloy composition, which was supported by in-situ diffraction analysis, and the whole process was controlled by diffusion. Its preferential formation was confirmed by annealing of powder mixture and by the experimental model as well. This model allowed observing the phases' formation at the interface of bulk nickel and molten aluminum at high temperature. The appropriate ongoing reactions were compiled for each alloy with calculated Gibbs energy and enthalpy of reaction.
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