Low-Temperature in Situ Large Strain Plasticity of Ceramic SiC Nanowires and Its Atomic-Scale Mechanism

Abstract

Large strain plasticity is phenomenologically defined as the ability of a material to exhibit an exceptionally large deformation rate during mechanical deformation. It is a property that is well established for metals and alloys but is rarely observed for ceramic materials especially at low temperature (∼300 K). With the reduction in dimensionality, however, unusual mechanical properties are shown by ceramic nanomaterials. In this Letter, we demonstrated unusually large strain plasticity of ceramic SiC nanowires (NWs) at temperatures close to room temperature that was directly observed in situ by a novel high-resolution transmission electron microscopy technique. The continuous plasticity of the SiC NWs is accompanied by a process of increased dislocation density at an early stage, followed by an obvious lattice distortion, and finally reaches an entire structure amorphization at the most strained region of the NW. These unusual phenomena for the SiC NWs are fundamentally important for understanding the nanoscale fracture and strain-induced band structure variation for high-temperature semiconductors. Our result may also provide useful information for further studying of nanoscale elastic−plastic and brittle−ductile transitions of ceramic materials with superplasticity.

The Mechanical Properties of Nanowires

“…This value might be slightly overestimated due to the use of a simple mechanical model. In situ TEM bending tests showed that SiC NWs could experience an elastic strain of ∼2% 232. However, the result might be affected by EBI in TEM.…”

Atomic-scale microstructure underneath nanoindentation in Al-Cr-N ceramic films

“…In general, dislocations are easily generated on close-packed planes where dislocations slip with low resistance. [34][35][36][37] So we examined the dislocations on close-packed planes along several directions in the obtained TEM micrographs. Away from the zone of indentation impression, there are not so many dislocations comparing with the obvious pile-up of dislocations around grain boundaries underneath indenter impressions.…”

Growth of ZnSe Nanospirals with Bending Mediated by Lomer−Cottrell Sessile Dislocations through Varying Pressure

“…Actually, with the reduction in dimensionality, nanostructures exhibit unique mechanical behavior, which has been demonstrated in various nanostructures. 15,16 Carbon nanotube sheets with tunable Poisson's ratio from positive to negative have been synthesized, 15 and a large strain plasticity of ceramic SiC nanowire at nearly room temperature has been directly observed in situ by a highresolution transmission electron microscopy (HRTEM) technique. 16 In this paper, we report on the unconventional growth of 1D ZnSe nanospirals via a two-stage fabrication process in which different reaction pressures are applied.…”

“…15,16 Carbon nanotube sheets with tunable Poisson's ratio from positive to negative have been synthesized, 15 and a large strain plasticity of ceramic SiC nanowire at nearly room temperature has been directly observed in situ by a highresolution transmission electron microscopy (HRTEM) technique. 16 In this paper, we report on the unconventional growth of 1D ZnSe nanospirals via a two-stage fabrication process in which different reaction pressures are applied. The morphological and structural characterizations are performed in section 3.1, which shows that ZnSe nanospirals with novel mosaic blocks compartmentalized by planar defects are obtained.…”