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Download fileFaceting, Grain Growth, and Crack Healing in Alumina
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posted on 2018-08-03, 00:00 authored by Pankaj Rajak, Rajiv K. Kalia, Aiichiro Nakano, Priya VashishtaReactive molecular dynamics simulations
are performed to study
self-healing of cracks in Al2O3 containing core/shell
SiC/SiO2 nanoparticles. These simulations are carried out
in a precracked Al2O3 under mode 1 strain at
1426 °C. The nanoparticles are embedded ahead of the precrack
in the Al2O3 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 Al2O3 matrix at the interface of SiC/SiO2 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 Al2O3 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.