FORMATION OF THE INTERMETALLIC COMPOUND VSI2 AND A VSI2-SIC COMPOSITEBY MECHANICAL ALLOYING

Powder mixtures corresponding to the compositions V33.3Si66.7, V25Si50 (SiC)25 and V20Si60C20 (at.%) were mechanically alloyed starting from elemental vanadium, silicon and carbon as well as silicon carbide powd ers. The alloying process was monitored by X-ray diffraction and therm al analysis. It was found that the intermetallic compound VSi2 and a V Si2-SiC composite with homogeneous and nanocrystalline structure were obtained by high energy ball milling. The opposite effect of SiC and C on the reactions between vanadium and silicon was discussed. The anne aling behaviour of mechanically alloyed powders was studied by differe ntial thermal analysis. The fast diffusion of silicon atoms into the v anadium matrix is suggested to control the solid state reactions betwe en V and Si in the annealing processes.