Researchers at The Ohio State University (OSU), Columbus, and their partners are building a database of new titanium alloys that, they say, will be used to reduce the stress that pins, plates, and other medical implants put on healthy bones. A recent $1 million grant from the National Science Foundation’s Designing Materials to Revolutionize and Engineer our Future initiative will fund three years of research efforts and support graduate students who will work with undergraduates on the project.
They are collaborating with colleagues at Penn State, University Park, to build the database that will provide a reference guide to properties of alloys on the molecular scale. Other researchers will be able follow the guide like a cookbook to formulate titanium alloys for different applications, particularly medical implants.
Plain titanium is strong, nontoxic and easy to work with. However, it isn’t an ideal implant material, they explained. Bones naturally flex to absorb some of the impact of our movements. Titanium is less flexible, so wherever it connects to bone in the body, the titanium side of the connection flexes less than the bone. This stress and strain weakens the bone over time, and can break the connection to the implant, or break the bone itself.
So the researchers would like to determine how to increase titanium’s flexibility while retaining its more desirable qualities. They believe that adding bits of other chemical elements to titanium could create alloys that more closely match with bone. But which elements to add, and how much to add, are open questions. And while humans have been creating alloys for millennia, the process is traditionally slow and labor-intensive. Research colleagues at Penn State will be supplying the computer simulations to speed things up.
OSU engineers will place small pieces of metal close together and heat them to high temperatures, so that atoms on the edges quickly diffuse to form just a sliver of alloy with a range of compositions between the metals. The sliver’s structure can be quite complex, depending on how many materials combine to form it and how wide a composition range it covers. They will use microscopy to study the alloys’ structures on a molecular level, and ultrafast laser-based methods to probe the alloys’ properties.