High-Strength and Ductile TiNbZrTa BCC MPEA With Heterogeneous Microstructure for Orthopedic Implants

Area of Science:

• Materials Science
• Biomaterials Engineering
• Metallurgy

Background:

• Developing advanced biomaterials for orthopedic implants requires alloys with excellent mechanical properties and biocompatibility.
• Multi-principal element alloys (MPEAs) offer tunable properties but require careful design for specific applications.
• Titanium-based alloys are widely used in biomedical applications, but improvements in strength and biocompatibility are continually sought.

Purpose of the Study:

• To design and develop a novel body-centered-cubic multi-principal element alloy (BCC MPEA) with enhanced mechanical and biological properties for orthopedic applications.
• To investigate the effect of Tantalum addition and heterogeneous structure design on the mechanical behavior and biocompatibility of TiNbZr alloys.
• To provide insights into the structure-property relationships for optimizing biomedical MPEAs.

Main Methods:

• Lattice distortion design principles were employed to introduce Tantalum (Ta) into a TiNbZr alloy.
• A heterogeneous microstructure was engineered to influence dislocation behavior.
• Mechanical properties were evaluated through yield strength and fracture elongation measurements.
• In vitro experiments assessed cell adhesion, proliferation, and osteogenic response.

Main Results:

• The developed TiNbZr_0.7Ta_0.3 alloy achieved a yield strength of 925.2 MPa and a fracture elongation of 26.1%.
• The heterogeneous structure, featuring recrystallized and unrecrystallized grains, facilitated dislocation mechanisms that balanced strength and ductility.
• In vitro studies showed enhanced cell adhesion, proliferation, and osteogenic response compared to the conventional TC4 alloy.
• The alloy exhibited significant heterogeneous deformation induced (HDI) stress effects due to hetero-structured interfaces and geometrically necessary dislocations (GNDs).

Conclusions:

• The Tantalum-modified TiNbZr alloy with a heterogeneous structure exhibits a remarkable combination of high strength, excellent ductility, and superior biocompatibility.
• The alloy is a highly promising candidate for orthopedic implant applications.
• This study offers valuable insights for the rational design of advanced biomedical MPEAs.