A 3D-Printed Ultra-Low Young's Modulus β-Ti Alloy for Biomedical Applications

Area of Science:

• Materials Science
• Biomedical Engineering
• Additive Manufacturing

Background:

• Metastable beta-titanium alloys are explored for biomedical applications due to their mechanical properties.
• Additive manufacturing offers novel routes to fabricate complex metallic components.
• Ti-21S alloy's potential for biomedical use requires detailed characterization, especially when processed via advanced techniques.

Purpose of the Study:

• To evaluate the metastable beta-Ti-21S alloy for biomedical applications.
• To characterize the microstructure and mechanical properties of additively manufactured Ti-21S.
• To assess the biocompatibility of the as-fabricated Ti-21S alloy.

Main Methods:

• Laser powder-bed fusion (L-PBF) was used to 3D-print near fully dense Ti-21S samples.
• Microstructural analysis was performed on the as-built material.
• Mechanical testing, including tensile tests, was conducted to determine Young's modulus, yield strength, ultimate tensile strength, and elongation.
• Cytotoxicity tests were performed to assess biocompatibility.

Main Results:

• Near fully dense (99.75%) Ti-21S samples were successfully fabricated via L-PBF.
• The as-built material consisted solely of metastable beta-phase with columnar grains.
• An exceptionally low Young's modulus (52 GPa) was observed, alongside high mechanical strength (yield strength 709 MPa, UTS 831 MPa) and total elongation (21%).
• Cytotoxicity tests confirmed good biocompatibility.

Conclusions:

• Additively manufactured Ti-21S alloy exhibits a unique combination of a low Young's modulus, good mechanical strength, and high ductility.
• These properties, coupled with confirmed biocompatibility, make Ti-21S a promising candidate for biomedical parts.
• The as-built condition, without post-processing heat treatment, provides properties comparable to wrought alloys and heat-treated Ti grade 5.