(557c) Heterogeneous Oxidation of Mechanically Alloyed Al-Mg Powders By Water and Oxygen

Alloys of aluminum and magnesium are widely used in pyrotechnics as well as in other energetic formulations.  They were also explored recently as metal additives in oxygen generators and as materials capable of reacting with water for hydrogen production.  Thus, mechanisms of low-temperature, heterogeneous oxidation of such alloys by both oxygen and water are of interest.  Understanding such mechanisms enables one to model both their aging and initiation in various devices.  In this work, mechanically alloyed Al-Mg powders are prepared and oxidized in controlled environments using thermo-gravimetry and microcalorimetry.  Both scanning experiments in a broad range of heating rates and isothermal micro-calorimetry experiments are performed.  Air, argon-water, and air-water oxidizing environments are considered.  Fully and partially reacted powders are characterized using electron microscopy and x-ray diffraction. Results will be presented and discussed in terms of the possible reaction mechanisms.