• In-situ alloying with boron during laser powder bed fusion refines the prior β grain size of Ti-6Al-4V from 200 μm to 50 μm, leading to a 15% increase in yield strength and a 20% improvement in elongation.
• The addition of 0.5 wt% boron results in a uniform distribution of boride precipitates, which contribute to grain boundary pinning and enhanced mechanical properties.
• The study demonstrates a cost-effective and scalable method to tailor the microstructure of additively manufactured titanium alloys without post-processing heat treatments.
• The findings open new avenues for designing high-strength, ductile titanium components for aerospace and biomedical applications.