Direct nitridation of titanium pellet is generally treated based on a
grain model of gas-solid reaction in which chemical reaction and pore
gas diffusion are taken into consideration. The morphologies of react
ion fronts in the titanium pellet in various control regions are diffe
rent. The progress of the reaction front of the grain of different pos
ition in the pellet has been shown in this study. Photographs of parti
ally reacted pellet and concentration profiles of solid reactants and
solid products determined by X-ray diffraction, are used to verify the
model predictions.