In Situ TEM Heating Study on the Oxidation and Shell-Breaking Characteristics of Aluminum Nanoparticles with Different Diameters

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The particle size of aluminum nanoparticles (ANPs) has a significant effect on the oxidation process. In this paper, the dynamic oxidation process of four ANPs (63, 132, 156, and 180 nm) was observed by in situ transmission electron microscopy. Variation rules in alumina shell thickness, particle size, and active aluminum content were identified, and reasons for the different oxidation phenomena for different ANPs were analyzed. The analysis shows that different ANPs exhibit different oxidation and shell-breaking phenomena at high temperatures. The temperature of complete oxidation of ANPs increases with their diameter. The form of expression of shell-breaking is the production of protrusions, and the protrusions are mainly caused by the accumulation of internal stresses and crystal transformation. The variation rule of diameter is related to the different oxidation phenomena of the ANPs due to the production and development of protrusions; its variation is mainly concentrated in the 800–1000 °C range. This research uncovers the oxidation process and mechanisms of ANPs of different diameters, offering insights to enhance energy release efficiency.