Processing of aluminum powder metallurgy alloys containing self-propagating reaction products

Powders of aluminum and iron oxide were subjected to high energy ball milling. A highly exothermic self-propagating reaction occurred during milling for iron oxide concentrations of 15 mol% or greater, leading to the formation of AlFe. In this case, the time required to trigger the instantaneous reaction depended exponentially on the charge ratio with the shortest time being approximately two hours. For concentrations of 10 mol% or less iron oxide, high energy ball milling provided intimate mixing of aluminum and iron oxide but did not trigger any reactions. In the milled powder mixtures with 10 mol% or less Fe2O3, the reaction to form AlFe can be triggered through the use of a subsequent heat treatment. For low charge ratios (CR = 1:1), AlFe formed at high temperatures (900-1100 degrees C). For high charge ratios (CR = 6:1) it formed at low temperatures (in the vicinity of the melting point of aluminum).