The initiation and reaction mechanism of nano-Al and nano-Al thermites in rapid heating environments is investigated in this work. A semiconductor-based grid/stage was used, capable of in situ heating of a sample from room temperature to 1473 K, and at a rate of 106 K/s106 K/s, inside an electron microscope. Nano-Al was rapidly heated in a transmission electron microscope, and before and after images indicate that the aluminum migrates through the shell, consistent with a diffusion-based mechanism. A nano-Al/WO3Al/WO3 composite was then heated in a scanning electron microscope. The results indicate that a reactive sintering mechanism is occurring for the nano-Al/WO3Al/WO3 thermite, as the products are found to be in surface contact and significantly deformed after the heating pulse.
Heated nano Al and nano Al/WO3 thermites at rapid rates. Al forms a native oxide of a few nanometers and when heated the Al will diffuse through the oxide shell. Reactions and structural changes occur where the nano Al and oxidizer were in close proximity.
Imaged in both the TEM (JEOL 2100) and SEM (Hitachi SU-70).