DIFFERENT PATHWAYS OF PHASE-TRANSITION IN A V-SI SYSTEM DRIVEN BY MECHANICAL ALLOYING

Solid state reactions induced by mechanical alloying of an elemental p owder mixture of V and Si with a composition of V75Si25 were investiga ted using X-ray diffraction and scanning and transmission electron mic roscopy. It was found that the phase transitions in this system are cl osely related to the milling intensity. High-energy milling mainly cau ses the formation of intermetallic compounds, whereas low-energy milli ng leads to amorphization. The thermodynamics and kinetics related to the different pathways of V-Si phase transition are briefly discussed in this paper. The effect of air contamination on phase transition is also addressed. (C) 1998 Elsevier Science Ltd.