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 (Nb_I and Nb_II) with a different lattice parameter. The intensities of Nb_I peaks on X-ray diffraction patterns decreased with the milling time and disappeared completely after 180 h of milling while the intensities of Nb_II 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.