Thermodynamic Prediction Of The Diffusion Barrier Morphology In The Al/Ni – Nano-Foil Designed For The Self-Propagating Reaction

Abstract

Thermodynamic model for the diffusion barrier formation in the Al/Ni nano-foil is presented. Two types of diffusion are distinguished in the model, boundary diffusion for substrate dissolution and bulk diffusion for solidification. The creation of two phases: Al 3 Ni, Al 3 Ni 2 in the diffusion barrier are predicted due to the cyclical manner of the dissolution and solidification occurrence.Keywords: meta-stable solidification; inter-metallic phases; diffusion barrier Przedstawiony jest termodynamiczny model formowania bariery dyfuzyjnej w nano-folii Al/Ni. Wyróżniono dwa typy dyfuzji, dyfuzję graniczną dla rozpuszczania oraz dyfuzję objętościową dla krystalizacji. Przewidziano tworzenie się dwu faz: Al 3 Ni, Al 3 Ni 2 w barierze dyfuzyjnej stosownie do cyklicznego przebiegu rozpuszczania i krystalizacji.

Inverse Model for the Solute Micro-Field Formation during Self-Propagating High Temperature Reaction

“…These intermetallic phases form a kind of a diffusion barrier and complicate the SHS -reaction. It was also proved that the intermetallic phases formation is the result of both Ni -substrate dissolution and subsequent meta-stable solidification of the dissolved zone which became liquid, [3]. In fact, the metastable dissolution of aluminum in the Ni -substrate leads to the formation of the liquid film in the Ni -sub-layers, as justified thermodynamically, Fig.…”

“…However, in the more realistic situation the AlNi -phase should exhibit its melting temperature higher than the melting point for the N F -solution. The N F -equilibrium solution is always formed due to the nickel diffusion into liquid aluminum, [3]. It is not possible to preserve pure aluminum in such a system, [3].…”

“…The N F -equilibrium solution is always formed due to the nickel diffusion into liquid aluminum, [3]. It is not possible to preserve pure aluminum in such a system, [3]. The current solution to the diffusion equation, Eq.…”

“…Instead of that, the meta-stable Al 3 Ni 2 -phase is created, [3]. The formation of the Al 3 Ni 2 -intermetallic phase as the result of peritectic reaction between AlNi and adequate liquid would be possible during the initial transient stable solidification, only.…”