Stability of lamellar microstructures in a Ti–48Al–2Nb–2Cr alloy during heat treatment and its application to lamellae alignment as a quasi-seed

• Microstructure stability of Ti–48Al–2Cr–2Nb alloy during heat treatment is studied.
• Lamellae orientation of Ti–48Al–2Cr–2Nb alloy is retained well upon rapid heating.
• A quasi-seed is used to align the lamellar microstructure of Ti–48Al–2Cr–2Nb alloy.

The stability of lamellar microstructures in the Ti–48Al–2Nb–2Cr alloy during heat treatment depends more on heating rate and less on holding time and cooling rate. When the heating rate is higher than 61 °C/min, the original lamellae orientation at room temperature can still maintain unchanged even though the lamellae are transformed to single α grains at a temperature close to melting point. Therefore, the high-temperature α grains, which are transformed from the α2/γ lamellae within a quasi-seed, are successfully employed to align the lamellar microstructure by directional solidification.