Effect of thermal stabilization on microstructure and mechanical property of directionally solidified Ti–46Al–0.5W–0.5Si alloy

Effect of thermal stabilization on the microstructure and mechanical property of directionally solidified Ti–46Al–0.5W–0.5Si (mole fraction, %) alloy was investigated. The specimens were thermal stabilized for different time (t) and directionally solidified at a constant growth rate of 30 μm/s and temperature gradient of 20 K/mm. Dependencies of the primary dendritic spacing (λ1), secondary dendritic spacing (λ2), interlamellar spacing (λL) and microhardness (HV) on holding time were determined. The values of the λ1, λ2 and λL increase with the increase of t, and the value of HV decreases with the increase of t. The increase of t is helpful to obtain a good directional solidification structure. However, it reduces the mechanical property of the directionally solidified TiAl alloy. The optimized value of t is about 30 min.