Direct Observation of Super‐Plasticity of Beta‐SiC Nanowires at Low Temperature

Abstract

Super‐plasticity of single‐crystal beta‐SiC [111] nanowires for > 200 % elongation was observed by in situ axial‐tensile experiments in a scanning electron microscope. The SiC nanowires were characterized by a bamboo‐like structure appearing as the 3C structured segments intergrowth along the nanowire. The axial localized plasticity and super‐plasticity are suggested to result only from the 3C segments, through dislocation generation, propagation and amorphization in contrast to the highly defected structural segments that conduct elastic‐deformation only, owing to the lack of slip systems. These results provide key information for understanding the mechanical behavior of SiC nanowires.

Understanding large plastic deformation of SiC nanowires at room temperature

“…Almost at the same time, super-plasticity was found during uniaxial tensile loading of SiC NWs, with local strain exceeding 200%. The observed super-plasticity was assumed to be due to dislocation nucleation, propagation and amorphization developed from cubic (3C) singlecrystal segments [11,12]. However, most of the analysis of tensile and bending deformation in SiC only revealed elastic behavior and brittle failure [13][14][15][16].…”

Micropillar compression inside zirconia degraded layer

“…In effect, a ductile behavior could be observed by reducing the sample size below some critical value that lies roughly between tens and hundreds of nanometers. Several materials conventionally known as "brittle" have shown plasticity features at the small scale: Si [16], GaAs [17], MgO [18] Al 2 O 3 [19] and SiC [20]. At the same time, superelastic and shape-memory effects were recently observed by Lai et al [21] during compression of tetragonal zirconia micropillars highly doped with Y and Ce.…”

Materials can be strengthened by nanoscale stacking faults

“…A disordered stacking sequence yields SFs, as shown in fig. 1(a) by dark stripes vertical to the axis of a [111]-oriented SiC nanorod (NR) [12]. Figure 1(b) is a model that contains uniformly distributed SFs, with a parallel spacing of 5 nm between neighboring SFs (hereafter referred to as the SF parallel spacing d).…”