Combined First-Principles and Experimental Study on the Microstructure and Mechanical Characteristics of the...

Area of Science:

• Materials Science
• Biomaterials Engineering
• Computational Materials Science

Background:

• Beta-stabilized titanium (β-Ti) alloys are promising for bone implants due to their low elasticity.
• The origin of this low elasticity in β-Ti alloys remains largely unknown.
• Understanding the elastic properties is crucial for optimizing implant performance.

Purpose of the Study:

• To elucidate the origin of low elasticity in β-Ti alloys.
• To investigate the microstructure, structural stability, mechanical characteristics, and electronic structure of Ti-35Nb-7Zr-5Ta (TNZT) alloy.
• To correlate bonding mechanisms with elastic properties.

Main Methods:

• Combined first-principles Density Functional Theory (DFT) calculations.
• Experimental analysis of microstructure, mechanical properties (hardness, Young's modulus), and electronic structure.
• Characterization of Ti-35Nb-7Zr-5Ta (TNZT) alloy produced via electron-beam powder bed fusion (E-PBF).

Main Results:

• The E-PBF manufactured TNZT alloy exhibits homogeneous mechanical properties (H = 2.01 ± 0.22 GPa, E = 69.48 ± 0.03 GPa).
• TNZT displays a mixed metallic and covalent bonding character.
• Softening in Cauchy pressure (C' = 98.00 GPa) and elastic constant C̅ = 23.84 GPa, attributed to weaker second and third neighbor bonds, is identified as the origin of low elasticity.

Conclusions:

• The low elasticity of TNZT alloys originates from specific bond weaknesses, particularly in second and third neighbor interactions.
• TNZT alloys are excellent candidates for orthopedic internal fixation devices.
• These findings provide a basis for predicting and designing mechanical and elastic properties of novel β-Ti alloys.