Method of mechanochemical synthesis for the production of nanocrystalline Nb-Al alloys

The solid-state synthesis of nanocrystalline alloys upon co-milling of niobium, aluminum, and chromium in a planetary mill was studied using X-ray diffraction and differential scanning calorimetry. Various Nb3Al-based powder nanocrystalline alloy with chromium additions were synthesized; after high-energy milling, the block sizes were equal to about 20 nm. It was shown that the complete dissolution of chromium and partial decomposition of the supersaturated Nb(Al) solid solutions occurs only after heating to 1100degreesC. Using mechanical alloying with niobium, the two-phase Nb3Al + Nb2Al alloy produced by arc melting was transformed into the two-phase Nb3Al + Nb(Al) alloy, which was confirmed by the quantitative X-ray analysis of the mechanosynthesized specimens heated to 1100degreesC. It was shown that the formation of niobium aluminides upon mechanochemical synthesis from components and mechanoactivation of Nb-Al intermetallic compounds enriched in niobium always occurs through the stage of formation of supersaturated solid solutions. The mechanism of this process can be connected with the formation of stacking faults upon deformation.