LAUSR

Abstract The Ti-22Al-24Nb-0.5Mo alloy was exposed at 1050 °C in the α2 + B2 two-phase region for various current-assisted heat treatment (CAHT) time. The effects that the heating time had on phase transformation, recrystallization, and texture evolution of the Ti-22Al-24Nb-0.5Mo alloy were systematically investigated using scanning electron microscopy coupled with electron backscattered diffraction (SEM-EBSD). The results showed that O → B2 + α2 and α2 → B2 transformation occurred during the CAHT process, where the O phase transformed into B2 phase at a relatively rapid rate, and the transformation rate of α2 to B2 was relatively slow. As the CAHT time increased, the B2 grains recrystallized (t = 0.5–10 min) and the secondary recrystallization (t = 15 min) were expressed as the Miller index of (112) [ 0 3 ¯ 1 ], and the microstructure and texture orientation changed significantly during the CAHT process. Tensile tests were performed at 970 °C to study the high-temperature performance of the as-received sheet and the sheets following the various CAHT time. The work hardening, dynamic recovery softening and grain coarsening process existed simultaneously in the alloy at high temperatures. When the CAHT time was 1 min, the superplastic tensile property of the sheet was the best with the elongation of 224.6%, which corresponded to the smallest and the largest sizes and the number of fracture cavities.