| Self-propagating high-temperature synthesis (SHS) of Ti_5Si₃, Ti_5Si₄ and TiSi has been investigated by ball milling of Ti-37.5at%Si, Ti-44.4at%Si and Ti-50.0at%Si powder mixtures. Ti and 60min pre-milled Si powders were milled by a high-energy ball mill. SHS reactions were observed to produce three Ti silicide phases during ball milling. Each critical milling period for the formation of Ti_5Si₄, Ti_5Si₃ and TiSi was found to be 16.5, 18.5 and 19.5 min, respectively, which were shorter than that of the ball milling using as-received and Si powders. The powders ball-milled after the critical milling period showed a rapid increase in micro hardness. The Hv values were found to be higher than 1000 kgf/㎟. The SHS reaction rates for the formation of the Ti silicides appeared to depend on the refinement of Si powder as well as the heat of formation of the products (Ti_5 Si₄→-81.0 kJ/㏖.at., Ti_5Si₃→-72.5 kJ/㏖.at., TiSi → -64.9 kJ/㏖.at). |
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