Influence of kinetic energy on the formation of Mg2Si

The intermetallic compound Mg 2 Si has been synthesized from elemental Mg and Si powders by ball milling. The rate of formation of Mg 2 Si was dependent on the size of milling balls. By using different ball sizes and combinations of balls of various sizes in a planetary ball mill, kinetic energy of ball milling was varied. Experimental results showed that small balls may induce faster reactions between Mg and Si compared with bigger balls, although the angular speed was kept constant. The mechanism of the faster reaction with smaller balls is being discussed. Theoretical simulation showed that the total impact energy using smaller balls is higher than that using larger balls, even though the impact energy per hit is much higher with larger balls. This phenomenon is associated with the change in impact angle. Theoretical simulation showed that the efficiency of impact energy decreases with increasing ball size as a result of the change in impact angle.