Phase formation during mechanical alloying in the Ti-Si system

초록

Mechanical alloying of Ti-Si powder mixture or TiH1.924-Si powder mixture was performed by high-energy ball milling, in which the Ti to Si mole ratio was 1:2. The phase formations in both mixtures during milling were investigated by X-ray diffraction. Mechanical alloying a mixture of elemental powders led to the formation of TiSi2 equilibrium compound, while when starting from Si + TiH1.924, a metastable phase was formed. The metastable phase completely transforms to TiSi2 when the mechanically alloyed powder is annealed at temperatures above 800 degrees C. Two different pathways of phase transitions during mechanical alloying are attributed to the existence of hydrogen atoms, i.e., when starting from Si + TiH1.924 compared to Si + Ti, the kinetics for the formation of the TiSi2 intermetallic compound slows down. The kinetics related to the different phase transitions depending on the starting powder mixture are discussed. (c) 2006 Elsevier B.V. All rights reserved.

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