Direct Visualization of Aluminum Particle Wetting on Carbon Using In Situ Laser Heating TEM

The fundamental understanding of aluminum particle wetting is critical for many industrial and military applications, such as nanocomposites, surface coatings, and explosives. In this study, the wetting behavior of aluminum particles on carbon is directly visualized using an in situ laser heating transmission electron microscope (ILH-TEM). Morphological, structural, and chemical analyses of the reaction products formed after laser irradiation of the aluminum–carbon system are characterized ex situ by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) using imaging, diffraction, and electron energy loss spectroscopy (EELS). Different stages of the wetting were captured for ex situ analysis by exposing the samples to a varying number of laser pulses. Additionally, molecular dynamics (MD) simulations were carried out using a reactive force field (ReaxFF) to obtain an atomistic perspective of the aluminum–carbon interactions. The results show that dissolution and reaction occur during the wetting process and the spreading front advancement results from the reaction between aluminum and carbon at the triple line. The complete mechanism of aluminum wetting is discussed in detail, i.e., the impact of laser heating, breakdown of the passivation layer, and interaction of aluminum and carbon, resulting in wetting enhancement.