Abstract In this paper, a new way for γ-alumina synthesis was proposed, the raw material being aluminum powders obtained by high-energy milling of aluminum cans. This seems a good option for this metal recycling and energy saving, as well as hydrogen production. The materials were prepared by precipitation techniques, in which aluminum powders reacted with hydrochloric acid, giving aluminum chloride, which was subsequently transformed into aluminum hydroxide by reaction with ammonium hydroxide or sodium hydroxide as precipitant agents, and finally into γ-alumina by calcination. Results showed that the used preparation methods gave a γ-alumina structure, confirmed by XRD, with surface areas values (174 and 204 m2 g-1) close to those of a commercial γ-alumina Cyanamid Ketjen (180 m2 g-1) or an alumina prepared by a typical precipitation route (203 m2 g-1). Using sodium hydroxide as precipitant agent turned out to be more ecologically compatible since it did not release harmful environmental compounds.

The effect of heat treatment on crystallization behavior of Fe73.5B15Si10Nb1.5 alloy powder prepared by mechanical alloying was studied. The powder samples were prepared by mechanical alloying (MA) and for different milling times (1, 5, 25, 70 and 100 hours). Crystalline powders of iron, boron, silicon and niobium were sealed with tungsten carbide balls in a cylindrical vial under nitrogen atmosphere. The ball-to-powder weight ratio was 20 to 1. A Fritsch Pulverizette 5 planetary ball mill was used for MA the powders at room temperature and at 250 rpm. To study the microstructural evolution, a small amount of powder was collected after different milling times and examined by X-ray diffraction, using CuKalpha radiation (lambda = 0.15418 nm). The crystallization behavior was studied by differential thermal analysis, from 25 up to 1000 °C at a heating rate of 25 °C min-1.