Midas touch hardens titanium

Thanks to its strength and biocompatibility, titanium has become the metal of choice for medical implants. But by adding a little gold to titanium, researchers now report they can create a superior material (Sci. Adv. 2016, DOI: 10.1126/sciadv.1600319). The new compound, β-Ti₃Au, is four times as hard as pure titanium and many steel alloys. The researchers, led by Rice University’s Emilia Morosan, attribute its extreme hardness, in part, to short Ti–Au bonds and a large number of valence electrons. Harder materials are always desirable, Morosan says, but hardness alone is not enough for biomedical applications. The material must also be biocompatible, and many hard titanium alloys are not. Happily, β-Ti₃Au is. It also wears better than pure titanium, which translates to a longer lifetime for implants made from the material. “These properties make β-Ti₃Au a good candidate for prolonging the lifetime of various dental implants and replacement joints,” Morosan says. But the compound’s superior properties may also allow engineers to use it for new applications in medicine, drilling, and sporting goods, she notes.