Achieving Enhanced Tensile Strength-Ductility Synergy Through Phase Modulation in Additively Manufactured Titanium Alloys

Abstract

Additively manufactured titanium alloys have drawn significant attention in the field of aerospace applications for their high strength, low density, and biocompatibility. However, as-printed titanium alloys always faced the trade-off challenge suffering from poor strength or ductility, high thermal gradient and cooling rate generally lead to the anisotropy in microstructure and mechanical properties, resulting in poor strength-ductility synergy. In the present work, a strategy of phase modulation has been proposed for a better strength-ductility synergy of titanium alloys. This approach achieved successive evolution from near α-Ti alloys to α+β alloy then to near β-Ti alloys. Significant strength enhancement with moderate ductility in TA15-x alloys is mainly due to the solid solution strengthening, grain refining strengthening and grain boundary strengthening brought about by phase modulation. Meanwhile the generation of the refined α lamellas, equiaxed α phase, discontinuous grain boundary α phase are of positive significance for the coordinated deformation of TA15-x alloy. Varying fracture modes demonstrated the potential of microstructure tailoring via multi-eutectoid elements alloying, facilitating the in-depth understanding of crack initiation, propagation, and strain-to-failure.

Keywords: Keywords: Titanium Alloys, Additive manufacturing, Phase modulation, Strength Enhancement, Fracture Mechanism