Effect of microalloying with rare-earth lanthanum on dynamic recrystallization behavior and mechanical properties of Ti sheets

Abstract

This study examines the influence of microalloying with rare earth lanthanum (La) on the dynamic recrystallization behavior and mechanical properties of Titanium (Ti) sheets. A distinctive wedge-shaped specimen was employed for experimental efficiency, enabling continuous gradient strains to be applied to the Ti-La alloy during hot-rolling, facilitating the assessment of changing microstructural, textural, and hardness features as strain increased from low to high levels. The hot-rolled plates were performed using analytical methods such as optical microscopy (OM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and hardness testing. The results show that the hardening process can be divided into four stages under continuous gradient strain (0 ∼ 0.5, 0.5 ∼ 0.7, 0.7 ∼ 1.2 and 1.2 ∼ 1.6). During these stages, grain refinement and dislocation strengthening emerge as critical contributors to changes in hardness. Furthermore, it was determined that dynamic recrystallisation (DRX) of Ti-La alloys during hot rolling occurs at the fourth stage. Analysis of the orientation distribution function (ODF) reveals that the dominant textures during this process include {1̅21̅0}, {011̅0}, and {0001} textures. When compared with commercially pure titanium (CP-Ti), the Ti-La alloy shows significantly delayed DRX under identical conditions. The DRX grain growth appears suppressed, attributable to the presence of La-rich particles on the grain boundaries. Moreover, the texture associated with rolling deformation seems subdued, providing a desirable base for future cold rolling and heat treatment.