Positive effect of hydrogen-induced vacancies on mechanical alloying of Fe and Al

Abstract

Nanocrystalline Fe82Al18 powders were prepared by high energy ball milling in various atmospheres. Two preparation techniques were compared: (i) mechanical milling of pre-alloyed Fe82Al18 pieces and (ii) mechanical alloying of pure Fe and Al powders.

Single phase Fe82Al18 nano-powder was formed by mechanical alloying in H-2 atmosphere while milling in N-2 or air environment suppressed mechanical alloying due to passivation of Fe surfaces. Positron annihilation spectroscopy revealed that mechanical alloying of Fe and Al in H-2 atmosphere is mediated by hydrogen-induced vacancies.

Keywords

• Nanostructured materials
• Mechanical alloying
• Vacancy formation
• Positron spectroscopies
• Mossbauer spectroscopy
• X-ray diffraction