MOLECULAR DYNAMICS SIMULATIONS OF LASER INDUCED SHOCK RESPONSE IN REACTIVE Ni/Al NANOLAMINATES

Abstract

To characterize the self-propagating, high-temperature exothermic alloying reactions of Ni/Al nanoscaled multilayered films induced by laser pulse shock loading, classical molecular dynamics simulations were performed. In the current work, a novel technique was developed to facilitate the energy input and distribution into nanolaminate thin films. The laser pulse shock loading technique enables the initial shock response of the material to be captured as well as the late-time mass diffusion controlled alloying reaction and Ni3Al formation. Shock compression raises the temperature, pressure, and density of the Ni and Al layers which triggers the Ni to diffuse into the Al and initiate the self-propagating alloying reaction. Thermodynamic states, enthalpy of reaction, and global reaction rates of the laminated films were obtained. It was determined that the series of complex rarefaction and reflection waves play a significant role in altering the thermodynamic state of the laminate. Attributes of the rarefaction and reflection waves are controlled by the geometry and thickness of the alternating layers. The dependence of layer thickness on the temperature, pressure, enthalpy of reaction, and global reaction rate was investigated and characterized.