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Titanium and carbon elemental powder mixtures with compositions of Ti 100−x C x ͑x =50,40,30͒ were milled under a helium atmosphere using a magnetoball mill. For Ti 50 C 50 and Ti 60 C 40 powder mixtures, the combined results of external mill temperature monitoring and x-ray diffraction ͑XRD͒ analysis indicated that, after a specific incubation period, titanium carbide ͑TiC͒ was formed rapidly via a highly exothermic mechanically induced reaction. However, contrary to the current understanding of mechanically induced self-propagating reactions, Raman spectroscopy clearly showed the formation of nonstoichiometric TiC in Ti 50 C 50 and Ti 60 C 40 powders prior to the sudden exothermic event occurring inside the mill. This result has not been reported in previous studies that used only XRD analysis to characterize the as-milled powders. It is now thought that a significant component of the heat generated after the incubation period may be due to a combination of rapid grain growth and/or recrystallization of the preexisting TiC, rather than the direct formation of TiC. When milling Ti 70 C 30 , the reaction to form TiC proceeded gradually as milling progressed.

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