The influence of partitioning on the growth of intragranular α in near-β Ti alloys



Publication Details

Li, T., Ahmed, M., Sha, G., Shi, R., Casillas, G., Yen, H., Wang, Y., Pereloma, E. V. & Cairney, J. M. (2015). The influence of partitioning on the growth of intragranular α in near-β Ti alloys. Journal of Alloys and Compounds, 643 212-222.


We report on partitioning of alloying elements during the formation of fine intragranular α plates in a Ti-55521 alloy after thermo-mechanical processing (TMP) and isothermal ageing at 923 K. The microstructures were characterised using atom probe tomography and high-resolution transmission electron microscopy. The partitioning of Mo, V and Al are strongly affected by their diffusivities and their mutual interaction. This leads to a deviation of the measured contents of alloying elements in the two phases from the predicted equilibrium values. The alloying elements at the broad faces and tips of α plates were found to exhibit different pile-up and segregation behaviours, which is thought to affect the lengthening and thickening kinetics of the α plates. As a result, the aspect ratio of α plates decreased rapidly with increasing ageing time. This study suggests that careful selection of alloying elements could be an effective way in controlling the growth anisotropy of α plates and thus α + β microstructures in near-β Ti alloys.

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