Superplasticity of silicon carbide

Nanocrystalline silicon carbide that was doped with boron and carbon (B,C-S iC) and contained 1 wt% boron additive and 3.5 wt% free carbon was fabricat ed using hot isostatic pressing under an ultrahigh pressure of 980 MPa and a temperature of 1600 degrees C, The average grain size of the material was 200 mm, The tensile deformation behavior of this material at elevated temp erature was investigated. The nanocrystalline B,C-SIC exhibited superplasti c elongation of >140% at a temperature of 1800 degrees C. High-resolution t ransmission electron microscopy observation and electron energy-loss spectr oscopy analysis revealed that this nanocrystalline SIC did not have a secon dary glassy phase at the grain boundary and the grain boundary had a strong covalent nature, which means that an intergranular glassy phase was not ne cessary to obtain superplasticity of covalent materials.