Properties of gas atomized Al-Fe powders and its variation by annealing

Properties of Ar gas atomized powders of Al-8mass%Fe alloy and its variation by annealing have been examined by means of scanning electron microscopy, transmission electron microscopy and hardness measurement. A cell structure having metastable phase AlmFe at its boundaries forms in particles in the size smaller than 105μm, besides a primary crystallized intermetallic compound Al3Fe predominantly exists in the particles larger than 105μm. The hardness of powders increases with decreasing particle diameter due to the refinement of cell structure. The annealing at temperature above 400°C accelerates the decomposition of cell structure and the formation of granular intermetallic compound, both of which result in the notable softening in the small size particles. AlmFe which has been at cell boun dariestransforms to Al3Fe by the annealing above 450°C. Even after high temperature annealing, large particles show only a slight decrease in hardness keeping low values due to a small change in the coarse structure.