Rice University physicists have discovered that a combination of titanium and gold provides a new standard for artificial knee and hip joints.
A 3-to-1 mixture of titanium and gold create a specific atomic structure that imparts hardness. The material's atoms are tightly packed in a “cubic” crystalline structure.
"It’s four times harder than pure titanium, which is what’s currently being used in most dental implants and replacement joints,” said lead scientist Emilia Morosan.
Morosan initially studied titanium-gold, a 1-to-1 ratio compound and magnetic material made from nonmagnetic elements. After being unable to grind the compound into powder for X-ray purposes, the researcher experimented with other combinations of the two elements.
One of the extra compounds was a mixture of three parts titanium and one part gold that had been prepared at high temperature.
Making titanium-3-gold at relatively high temperature produces an almost pure crystalline form of the beta version of the alloy — the crystal structure that is four times stronger than titanium.
At lower temperatures, the atoms tend to arrange in another cubic structure — the alpha form of titanium-3-gold, which is about as hard as regular titanium.
Morosan's group plans to conduct follow-up tests to further investigate the crystal structure of beta titanium-3-gold, and to see if chemical dopants might improve its hardness even further.
