A method for producing a particulate aluminum alloy involves pulverizing an aluminum alloy in a hydrocarbon solvent in the presence of an organic aluminum compound. Methods for producing trialkylaluminum involve reacting an aluminum-magnesium alloy with an alkyl halide in the presence of a nitrogen-containing organic compound to obtain a trialkylaluminum-containing reaction product, and reacting an aluminum-magnesium alloy and an alkyl halide. A highly active, low viscosity composition containing the particulate aluminum alloy and a method for producing the particulate aluminum alloy-containing composition are also described.