Scientists use tin to strengthen titanium alloys for implants

Artificial hip femoral components. The ternary interaction of titanium (Ti), β-stabilizing elements like niobium (Nb) and vanadium (V), and tin (Sn) plays a crucial role in determining the phase stability of the biocompatible Ti alloys. Credit: Tohoku University.

Researchers have found a way to make titanium alloys, commonly used in medical implants, even stronger and more reliable.

Beta (β)-type titanium alloys are popular for their strength, flexibility, and resistance to tough environments.

These properties, along with their excellent compatibility with the human body, make them ideal for implants and prosthetics like joint replacements and stents.

However, these alloys can sometimes form a brittle phase called omega, which makes them prone to breaking.

Scientists knew that adding tin (Sn) could prevent this issue and make the alloys stronger, but the exact reason why remained a mystery until now.

A team led by Norihiko Okamoto and Tetsu Ichitsubo from Tohoku University’s Institute for Materials Research has uncovered the mechanism behind this strengthening effect.

They used a combination of experiments and theoretical analyses with model titanium–vanadium (Ti–V) alloys to make their discovery.

“Our findings reveal that the interaction between titanium (Ti), vanadium (V), and tin (Sn), along with the anchoring effect of Sn atoms, work together to completely suppress the formation of the harmful omega phase,” explained Ichitsubo.

This process is known as the “cocktail effect.”

The cocktail effect in metallurgy refers to the phenomenon where mixing multiple elements in a balanced way results in materials with superior properties.

Just like blending various drinks can create a delicious cocktail, combining different elements can enhance the performance of alloys.

“This discovery highlights the importance of considering multi-element interactions in alloy design, not just for biomaterials but also for other applications,” said Okamoto.

Understanding how to strengthen β-type titanium alloys will help improve biomedical implants, providing better support for people with degenerative bone conditions or those in aging populations.

The study, published in the journal Acta Materialia on April 29, 2024, was inspired by the work of pioneering scientists Shuji Hanada and Naoya Masahashi from Tohoku University.

This breakthrough in alloy design could lead to the development of even more advanced materials for medical and other high-performance applications.