The evolution of modulated elemental reactants containing alternating layer
s of carbon and Ti, W, or Mo was studied using differential scanning calori
metry and X-ray diffraction. TiC crystallized at 350 degreesC from a modula
ted reactant with a composition near 1:1 with respect to Ti and C. Mo2C and
W2C nucleated at 500 and 600 degreesC, respectively, from modulated reacta
nts with compositions close to their stoichiometry. No exotherms were obser
ved in samples that had compositions that were not close to the stoichiomet
ries of TiC, Mo2C, or W2C.