Faceting, Grain Growth, and Crack Healing in Alumina.
basic_science · Level V
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- Record sourced from PubMed, PMID 30074760.
- Also identified by DOI 10.1021/acsnano.8b02484.
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Abstract
Reactive molecular dynamics simulations are performed to study self-healing of cracks in Al<sub>2</sub>O<sub>3</sub> containing core/shell SiC/SiO<sub>2</sub> nanoparticles. These simulations are carried out in a precracked Al<sub>2</sub>O<sub>3</sub> under mode 1 strain at 1426 °C. The nanoparticles are embedded ahead of the precrack in the Al<sub>2</sub>O<sub>3</sub> matrix. When the crack begins to propagate at a strain of 2%, the nanoparticles closest to the advancing crack distort to create nanochannels through which silica flows toward the crack and stops its growth. At this strain, the Al<sub>2</sub>O<sub>3</sub> matrix at the interface of SiC/SiO<sub>2</sub> nanoparticles forms facets along the prismatic (A) ⟨2̅110⟩ and prismatic (M) ⟨1̅010⟩ planes. These facets act as nucleation sites for the growth of multiple secondary amorphous grains in the Al<sub>2</sub>O<sub>3</sub> matrix. These grains grow with an increase in the applied strain. Voids and nanocracks form in the grain boundaries but are again healed by diffusion of silica from the nanoparticles.