Formation of (B2 + D03) phases at a/2〈1 0 0〉 anti-phase boundary in an Fe–23 at.%Al–8.5 at.%Ti alloy

The as-quenched microstructure of the Fe–23 at.%Al–8.5 at.%Ti alloy was a mixture of (A2 + D03) phases. Transmission electron microscopy (TEM) examinations indicated that when the alloy was aged at 900 °C, the size of the D03 domains increased with increasing aging time, and an A2 → (A2 + D03) → (B2 + D03) transition occurred at a/2〈1 0 0〉anti-phase boundaries (APBs). This feature has never been reported by other workers in the Fe–Al–Ti alloy systems.