Abstract
This paper compared the mechanical behavior of 6H SiC under quasi-static and dynamic compression. Rectangle specimens with a dimension of 3 × 3 × 6 mm3 were used for quasi-static compression tests under three different loading rates (i.e., 10−5/s, 10−4/s, and 10−3/s). Stress–strain response showed purely brittle behavior of the material which was further confirmed by scanning electron microscopy (SEM)/transmission electron microscopy (TEM) examinations of fractured fragments. For dynamic compression, split Hopkinson pressure bar (SHPB) tests were carried out for cubic specimens with a dimension of 6 × 6 × 4 mm3. Stress–strain curves confirmed the occurrence of plastic deformation under dynamic compression, and dislocations were identified from TEM studies of fractured pieces. Furthermore, JH2 model was used to simulate SHPB tests, with parameters calibrated against the experimental results. The model was subsequently used to predict strength and plasticity-related damage under various dynamic loading conditions. This study concluded that, under high loading rate, silicon carbide (SiC) can deform plastically as evidenced by the development of nonlinear stress–strain response and also the evolution of dislocations. These findings can be explored to control the brittle behavior of SiC and benefit end users in relevant industries.
Highlights
Silicon carbide (SiC) is a ceramic material with high strength, superior hardness and strong wear resistance even at elevated temperatures
4.1 Stress-strain response The stress-strain behaviour is compared in Fig. 6 for both the quasi-static and dynamic compression tests
In order to confirm if plastic deformation takes place under such loading condition, FIB lift-outs were carried out for fragments collected after quasi-static and dynamic uniaxial compression tests
Summary
Silicon carbide (SiC) is a ceramic material with high strength, superior hardness and strong wear resistance even at elevated temperatures. Lankford [16] tested Al2O3 at different temperatures (-196°C to 1526°C) and different strain rates (10-5/s to 103/s), and found that transgranular cracking, nucleated by twinning process (plastic deformation), was the dominant failure mechanism at low temperature and under quasi-static loading conditions. Different strain rate was adopted to study the static and dynamic deformation behaviour under uniaxial compression.
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