Microscopic plastic deformation in Ti2AlNb alloy micro-pillars: An <i>in situ</i> SEM study

Ti2AlNb alloys have attracted significant attention due to their excellent mechanical properties during the application in high-temperature environments. However, due to the significant experimental difficulties, the deformation behavior of Ti2AlNb alloys at microscale has been rarely investigated. Therefore, a series of in situ compression experiments for micropillars of Ti2AlNb alloys were performed by SEM, and the effect of microscopic structures was discussed based on experimental results and statistical analysis. Stress–strain curves of micro-pillars with different diameters were obtained. Apparent strain bursts exist in the stress plateau of micro-pillars with a diameter of 1 µm. With the increase in diameter, the yield strength of micro-pillars significantly decreased, showing a strong size effect. In situ observations reveal that the crystalline slip in the B2 matrix dominates the plastic deformation in Ti2AlNb micro-pillars. On the other hand, the intermittency of plastic deformation in Ti2AlNb micro-pillars was discussed based on probability statistical analysis. With an increase in the diameter of the micro-pillar, larger displacement jumps were more liable to occur, while smaller micro-pillars tended to exhibit fewer displacement jumps. The current study provides fundamental insights into the deformation behavior of Ti2AlNb alloys at microscale.