We discuss the limitations of the earlier models in explaining the evo
lution of diffuse scattering during the 2H to 6H direct transformation
in single crystals of SiC above 2000 degrees C. Monte Carlo technique
is employed to predict the diffuse scattering along c using a nuclea
tion and growth model. The results obtained by simulation are compared
with those obtained analytically, assuming sequential insertion of st
acking faults. The predicted diffraction effects are found to be in ag
reement with those observed experimentally. It is shown that the short
range and long range correlations are in conflict for the arrest stat
e of the 2H to 6H 'direct' transformation.