Investigation of the Cubic Boron Nitride Nucleation under the High Pressure and the High Temperature

In this paper we have theoretically found the activation energy ($420.38kJ\mathrm{/}mol$) for the transformation from hBN to cBN in the microscopic viewpoint. We have introduced an analytical formula representing the dependence of nucleus formation time on the activation energy, synthesis pressure and temperature. We have theoretically determined the boundary line of cBN nucleus formation region in the $P-T$ phase diagram on the basis of the diffusion mechanism of cBN nucleus formation. We have found that the cBN crystal nucleus formation time is less than $300ms$ by comparing of the theory and experiment.