From single to multi-gradients: microstructure and mechanical properties of additively manufactured Ti alloys

Gradient-structured materials provide an effective pathway for enhancing mechanical performance through spatially tailored composition and microstructure. Here, additive manufacturing is employed to fabricate Ti alloys with well-defined single- and multi-gradient architectures while maintaining an identical overall hardness contrast. The multi-gradient sample exhibits a much higher gradient rate, with hardness decreasing from 380 HV to 175 HV over a distance of 500 µm. Mechanical testing shows that the multi-gradient sample achieves higher tensile strength and ductility than the single-gradient counterpart. In-situ digital image correlation (DIC) reveals suppressed strain localization and delayed onset of fracture in the multi-gradient sample. These results highlight multi-gradient design as an effective and scalable strategy for enhancing the mechanical performance in additively manufactured alloys.