Figure 3 presents the β grain morphologies with martensiticα′ microstructure of TC4–DT alloy after heat treatments at 990 and 1030 °C for various holding times. The typical acicularα′within the prior β grain was obtained by quenchingfrom β region and observed in all the micrographs. Prior β grains were less distinct because

of no precipitation of grain boundaryα(αGB) under the rapid cooling.

Figure 3 presents the β grain morphologies with martensiticα′ microstructure of TC4–DT alloy after heat treatments at 990 and 1030 °C for various holding times. The typical acicularα′within the prior β grain was obtained by quenchingfrom β region and observed in all the micrographs. Prior β grains were less distinct because

of no precipitation of grain boundaryα(αGB) under the rapid cooling.