In situ observation of combustion to form TiN during ball milling Ti in nitrogen

Mechanical milling of Ti powder in nitrogen by a high-energy ball mill was performed. The pressure was monitored in situ. Initially, nitrogen was dissolved in Ti to form a solid solution. Under suitable conditions, when the nitrogen content had reached 32 at. %, the nitrogen pressure drastically dropped and instant formation of TiN took place. The TiN was formed by means of self-catalytic combustion, which was triggered by the high impact energy and the large clean surface of the fine Ti particles.