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 α2-Ti3Al phase in TiAl alloys exhibits brittleness at room temperature, making TiAl alloy susceptible to failure. Pulsed current (PC) could 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 Ti3Al single crystal by molecular dynamics simulation. It is found that the room-temperature flow stress decreases with the increasing PC density. The tunability of flow stress could be ascribed to the PC induced twin junction that is originated from the PC regulated body-centered cubic phase distribution in Ti3Al. 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 Ti3Al single crystals. Our findings on the PC induced twin junctions for tuning flow stress and strain delocalization in Ti3Al single crystals could provide new insights for the electrically assisted regulation of mechanical behavior of TiAl alloys.

Keywords: Pulsed current, Ti3Al single crystal, Twin junction, Flow stress, Strain delocalization, Molecular dynamics