Achieving 1.5 GPa superstrong Ti-6Al-4V using cold plastic deformed powder feedstock and laser additive manufacturing

Abstract

The Ti-6Al-4V alloy is the most widely utilized titanium metal alloy globally, making the enhancement of its mechanical properties important. In this study, we achieved an ultimate tensile strength of 1.5 GPa through the additive manufacturing (AM) of Ti-6Al-4V. Specifically, the Ti-6Al-4V alloy was fabricated via laser powder bed fusion (L-PBF) using Ti-6Al-4V powder subjected to cold plastic deformation (CPD Ti-6Al-4V). The microstructural evolution of the Ti-6Al-4V powder during CPD was analyzed in detail. The CPD Ti-6Al-4V powder exhibited a core-shell structure with subgrains and nanocrystals formed via high-density dislocations within the shell. In addition, the as-printed CPD Ti-6Al-4V alloy had an average grain size of approximately 1.9 μm. The presence of interstitial elements and finer grains resulted in the formation of Ti-6Al-4V alloys with ultrahigh strengths (ultimate tensile strength of approximately 1500 MPa, yield strength of 1320 MPa, and elongation of 6%). This groundbreaking achievement paves the way for further advancements in AM technology and presents exciting opportunities for innovation across a range of high-strength materials, which are crucial for achieving optimal performance.