Effect of Heat Treatment on Two-Phase Ti – 22Al – 25Nb Alloy Phase Composition and Microhardness.

The effect of heat treatment on evolution of the phase composition and microhardness of orthorhombic alloy Ti – 22Al – 25Nb based upon a Ti2AlNb phase (O-phase) is studied. X-ray diffraction, scanning electron microscopy, and electron back-scatter diffraction are used to study alloy phase composition after different treatments. It is shown that the alloy structure contains β/B2- and O-phases, the proportion of which changes on heat treatment. Microstructure and Vickers microhardness of alloy Ti – 22Al – 25Nb are shown to be interrelated in different states. [ABSTRACT FROM AUTHOR]