GOLD PLUS TITANIUM HARDEST KNOWN METALLIC SUBSTANCE (Orthopedics This Week)
A mixture of titanium and gold turns out to be the hardest known metallic substance that is compatible with living tissues, according to Helen Briggs, writing for the BBC News. This is potentially very good news for makers of hip and knee implants—which often must be replaced after a decade of use because of wear on the device. According to Briggs, Professor Emilia Morosan, Ph.D., of Rice University, Houston, Texas, and her team made the discovery while working on magnets made from titanium and gold.
Because the newly made gold and titanium material needed to be ground into a power to test it for purity, the researchers put it in a diamond-coated porter and pestle. However, the material was so hard that the researchers could not grind it into a powder with the diamond equipment. Morosan said that their Beta-Ti3Au, which they had named it, “showed the highest hardness of all Ti-Au [titanium-gold] alloys and compounds, but also compared to many other engineering alloys.”
Briggs noted that titanium is one of the few metals that human bone is able to grow around, allowing it to be used widely in medicine and dentistry. Morosan said the hardness of the substance, together with its higher biocompatibility, made it a next generation compound for substantively extending the lifetime of dental implants and replacement joints. She added that the gold-titanium alloy is a cubic compound with a particular arrangement of atoms found when metals are combined at high temperatures.