Mechanical alloying and microstructure of a Nb–20% V–15% Al alloy

A niobium-based alloy with 20% V–15% Al (at.%) was synthesized by mechanical alloying of elemental powders. During milling, the splitting of Nb X-ray peaks into two components was observed. Each component was found to correspond to a niobium solid solution (NbI and NbII) with a different lattice parameter. The intensities of NbI peaks on X-ray diffraction patterns decreased with the milling time and disappeared completely after 180 h of milling while the intensities of NbII peaks gradually increased. The powders were hot pressed and microstructural and phase analyses of the consolidated material were carried out. The microstructure consisted of Nb solid solution, Nb3Al-base intermetallic with the A15 crystal structure and dispersoid Al2O3. Also an unexpected, detrimental, Nb2Al-base σ phase was found. The volume fraction of the σ phase depended on the temperature of consolidation.