Leveraging high heating rates to attain desirable reaction products in Al/Zr/C nanocomposites

Reactive nanolaminates are a class of energetic materials which store significant chemical energy in their heterogeneous microstructure that comprises alternating nano-scaled layers of two or more reactants which can undergo self-propagating exothermic reactions to form stable compound phases. We previously observed that the products of self-propagating formation reactions in Al/Zr/C nanolaminates differ dramatically from those obtained after heating slowly to any temperatures up to 1450 °C. Here we explore this heating-rate dependent phase formation in Al/Zr/C reactive nanolaminates through a combination of nanocalorimetry coupled with in situ synchrotron X-ray diffraction, as well as a suite of ex situ analyses. Specifically, we show that forming a cermet of ZrC + Al requires either a sufficiently high heating rate (such as is present during a self-propagating reaction) or quenching from high temperatures (≈ 1600 °C), demonstrating the utility of high heating rates to produce desirable phases.