Work

Synergistic effect of boron and nitrogen on strength enhancement and anisotropy mitigation in Ti6Al4V fabricated via directed energy deposition

Year: 2025

Type: article

Abstract: Controlling the mechanical properties and microstructure anisotropies of additively manufactured Ti6Al4V alloys remains a challenge for improving their performance in demanding applications. Therefore, this study examined the effects of adding B and N on the microstructural evolution and mechanical properties of Ti6Al4V alloys fabricated using laser powder directed energy deposition (LP-DED). The SMART process, which is a novel composite powder fabrication method, was used to prepare feedstocks for LP-DED. This approach enabled control over the contents of B and N to optimize the microstructure and mechanical properties of the Ti6Al4V alloys. The addition of B resulted in effectively refined prior-β grains through constitutional supercooling and TiB precipitation. The addition of N resulted in the formation of a solid solution within the matrix without significant grain refinement. When B and N were added simultaneously, their individual roles in Ti6Al4V remained unchanged compared to their separate additions. However, the combined addition of B and N exhibited a synergistic effect, achieving a balanced improvement in both strength and elongation anisotropy. By deepening the understanding of B and N interactions in Ti alloys, these findings pave the way for a strategy to enhance structural reliability and suppress anisotropy in additively manufactured Ti6Al4V alloys for aerospace, automotive, energy, and biomedical applications.

Source: Journal of Materials Research and Technology

DOI: 10.1016/j.jmrt.2025.03.113

Authors: SeungHyeok Chung, Jae Joon Kim, Junghwan Kim, Seungchan Cho, Ho Jin Ryu, Taegyu Lee