Formation of Magnesium Silicide by Mechanical Alloying

Abstract

Elemental Mg and Si powders were mechanically alloyed in a planetary ball mill. The formation of magnesium silicide as well as the formation of magnesium oxide and hydride in the milled powders was studied in detail by X-ray diffraction and scanning differential calorimetry. It was found that direct formation of the magnesium silicide, Mg2Si, occurred after 10 hours of milling and the content of Mg2Si increased with increasing the milling duration. The activation energy for the formation of Mg2Si was calculated by the Kissinger approach to be 215 kJ/mol. Besides oxidizing and hydrizing of Mg by decomposed organic additives during mechanical alloying, an increased contamination of powders from steel and alumina milling tools with increasing milling duration was detected. A short milling duration followed by a thermal treatment was thus suggested to synthesize magnesium silicide.