Adding Gold to Titanium Strengthens Orthopedic Implants

A novel study reveals that an intermetallic compound of titanium and gold with a specific atomic structure imparts increased hardness to artificial joints.

Developed by researchers at Rice University (Rice; Houston, TX, USA), Texas A&M University (TAMU, College Station, TX, USA), and other institutions, β-Ti3Au exhibits hardness values about four times higher than those of pure Ti and most steel alloys, reduced coefficient of friction and wear rates, and biocompatibility, all of which compart to the compound optimal traits for orthopedic, dental, and prosthetic applications. An additional benefit is its ability to adhere to ceramic, which can reduce both the weight and the cost of medical components.

According to the researchers, the fourfold increase in the hardness of β-Ti3Au compared to other Ti-Au alloys can be attributed to the elevated valence electron density, the reduced bond length, and pseudogap formation. The specific arrangement that imparts ultra-hardness to the β form of the compound is due to relatively high temperatures that produce an almost pure crystalline form of the alloy. At lower temperatures, the atoms arrange in another cubic structure, α-Ti3Au, which has the same hardness as regular titanium. The study was published in the July 2016 issue of Science Advances.

“We published a study not long ago on titanium-gold, a 1-to-1 ratio compound that was a magnetic material made from nonmagnetic elements. One of the things that we do when we make a new compound is try to grind it into powder for X-ray purposes,” said senior author professor of physics and astronomy, chemistry, materials science, and nanoengineering Emilia Morosan, PhD, of Rice. “When we tried to grind up titanium-gold, we couldn't. I even bought a diamond-coated mortar and pestle, and we still couldn't grind it up.”

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