Chemical reactions in reactive powder metal mixtures during shock compression

Abstract

A heterogeneous chemical reaction model is proposed and used to describe shock-induced chemical reactions that occur in reactive granular mixtures during shock compression. The proposed heterogeneous model is intended for application in mesoscale simulations at locations where reactant particles are in contact. Previous studies have employed homogeneous reaction rate models with Arrhenius type kinetics, in which the material transport mechanism is not spatially dependent. In contrast, the spatially heterogeneous model explicitly describes material transport at the interface between the reactants. A transport mechanism permits reactants to flow through the product that is formed between the reactant grains during reaction. Diffusion mechanisms alone are too slow to describe shock-induced chemical reactions. Therefore, the stress contribution is included in the activation energy to affect both the diffusion rate and the surface reaction kinetics. The model is demonstrated for the 2Al+Fe2O3 system, in which the pressure and temperature initial conditions are obtained from a mesoscale simulation. Calculated temperatures are compared with previously reported experimentally measured shock temperatures, showing the capability of the proposed model to describe this shock-induced chemical reaction.