MICROSTRUCTURAL EVOLUTION IN MECHANICAL ALLOYED Mo-67%Si ELEMENTAL POWDERS MIXTURE
Mo,Si混合粉末的机械合金化

The microstructural evolution of mechanical alloyed Mo-67%Si powders using the planetary ball mill has been studied by X ray diffractometer (XRD) and differential thermal analyzer (DTA). The result shows that the hexagonal (h) MoSi2 and tetragonal (t) MoSi2 nanocrystallites formed in succession as the intermediate products of mechanical alloyed Mo/Si powders, and the final products are a mixture of h-MoSi2 microcrystallites and amorphous elemental Mo and Si powders.Additionally the reason why the h- MoSi2 phase predominates over t-MoSi2 phase in the mechanicalalloyed powders mixture has been explained on the basis of the concept of the nuclei of h-MoSi2 forming likely from the stacking faults on the {110} plane of t- MoSi2 phase during mechanical alloying process.For this reason, h-MoSi2 is a kind of low temperature metastable phase closer to amorphous state than t-MoSi2 in free energy.