Pulsed current induced twin junction for tuning flow stress and strain delocalization in Ti3Al single crystal

Abstract

TiAl alloys have garnered significant attention due to their excellent mechanical properties at high temperatures. However, the ${\alpha }_2$-Ti${}_3$Al phase in TiAl alloys exhibits brittleness at room temperature, making TiAl alloys susceptible to failure. Pulsed current (PC) can induce athermal electro-plasticity in metallic materials, and is thus possible to tune the microstructure and mechanical behavior of TiAl alloys. Herein, we explore the PC-assisted tuning of flow stress and strain delocalization at room temperature and the associated atomistic mechanisms in Ti${}_3$Al single crystal by molecular dynamics simulation. It is found that the room-temperature flow stress decreases with increasing PC density. The tunability of flow stress could be ascribed to the PC-induced twin junction that originated from the PC regulated body-centered cubic phase distribution in Ti${}_3$Al. By analyzing the shear strain distribution and microstructure evolution, the PC-induced twin junctions are revealed to effectively alleviate the local strain accumulation at twin boundaries, thus promoting the strain delocalization of Ti${}_3$Al single crystal. Our findings on the PC-induced twin junctions for tuning flow stress and strain delocalization in Ti${}_3$Al single crystal could provide new insights for the electrically assisted regulation of mechanical behavior of TiAl alloys.