Formation of Nanophase Niobium Aluminide by Mechanical Alloying

Mechanical alloying of an elemental powder mixture containing 51.5 mass%Nb; 43.0 mass%Al and 5.5 mass%Ti was carried out in an Argon-filled ball mill at ambient temperature for 90 to 1800 ks. MAed powders were examined by X-ray diffraction for changes in elemental particulate size and grain sizes of newly formed intermetallic phases. The elemental particulate size measured from the line-broadening decreased with increasing MA time up to 720 ks, while XRD identified the newly formed intermetallic phases, Nb 3 Al and NbAl 3 at and beyond 720 ks. Their grain sizes remained at a few nanometers level (3-8 nm). Differential scanning calorimetry (DSC) of MAed powders revealed both exothermic and endothermic reactions