A Novel Approach to Enhancing Mechanical Properties of Additively Manufactured Ti-6Al-4V Alloy via In-Situ Microalloying with Boron
Authors: John A. Smith, Emily R. Johnson, Michael T. Brown, Sarah L. Davis
Additive manufacturing (AM) of Ti-6Al-4V alloy often results in a coarse columnar grain structure that degrades mechanical properties. This study introduces a novel approach to refine the microstructure and enhance mechanical properties by in-situ microalloying with boron (B) during laser powder bed fusion (LPBF). Ti-6Al-4V powders with 0.1 wt% and 0.5 wt% B were processed, and the effects on microstructure and mechanical properties were systematically investigated. Results show that B addition promotes the formation of equiaxed grains and suppresses columnar growth, leading to a significant reduction in grain size. The 0.5 wt% B alloy exhibited a 25% increase in yield strength and a 15% improvement in ductility compared to the unmodified alloy, while maintaining comparable hardness. Electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analyses revealed that the refinement is attributed to the formation of TiB precipitates that act as heterogeneous nucleation sites. This work demonstrates that in-situ microalloying with B is a promising strategy to tailor the microstructure of AM Ti-6Al-4V for high-performance applications.
