First principles study of the C/Si ratio effect on the ideal tensile strength of β-SiC

Abstract

The C/Si atom ratio effect on the ideal tensile strength of β-SiC systems is investigated with first principles calculations. Monte Carlo (MC) simulations with empirical inter-atomic potential are used to generate non-stoichiometric SiC samples. Non-stoichiometric SiC super cells are stretched in [100] direction and the C/Si ratio ranges from 1 to 1.52. The calculation results show that higher carbon concentration will reduce the tensile strength because of the internal strain around the carbon clusters. Under a tensile strain loading, the sample will break at strained Si–C bonds or C–C bonds around carbon clusters. Especially, the tensile strength will drop dramatically for the existence of large carbon clusters. Long time MC process makes the size distribution of carbon clusters uniform and reduces the size of big carbon clusters. It suggests that in order to improve the tensile strength of SiC, samples with homogeneous distributed small size carbon clusters should be fabricated by a reasonable fabrication process in industry.