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, nitroge n was dissolved in Ti to form a solid solution. Under suitable conditi ons, when the nitrogen content had reached 32 at.%, the nitrogen press ure drastically dropped and instant formation of TiN took place. The T iN was formed by means of self-catalytic combustion, which was trigger ed by the high impact energy and the large clean surface of the fine T i particles. (C) 1997 American Institute of Physics.