Modeling of the self-propagating reactions of nickel and aluminum multilayered foils

Abstract

In this study, we performed simulations of self-propagating reactions of nanoscale nickel-aluminum multilayers using numerical methods. The model employs two-dimensional heat transfer equations coupled with heat generation terms from, (1) 1D parabolic growth of intermetallic phases Ni2 Al3 and NiAl in the thickness direction and (2) phase transformations such as melting and peritectic reactions. The model uses temperature dependent physical and chemical data, such as interdiffusion coefficients, specific heat capacities, and enthalpy of reactions obtained from previous independent work. The equations are discretized using a lagged Crank-Nicolson method. The results show that initially, the reaction front velocity is determined by the rapid growth of Ni2 Al3 and the front temperature is limited by the peritectic reaction at ∼1406 K. After the front completely traverses the foil and the temperature reaches the peritectic point, the reaction slows down and the temperature rises by the growth of NiAl which is the only stable phase at these temperatures. The reaction is completed when the initial constituents are consumed and the temperature reaches the melting point of NiAl. Subsequently, the foil cools and solidifies to the final phase dictated by the overall composition. The computational results show excellent fit to experimental velocity and temperature measurements. © 2009 American Institute of Physics.