Additive Manufacturing of Magnesium-Based Alloys

In a joint project between Swerim and Uppsala University we are aiming to combine the beneficial properties of magnesium alloys, such as biocompatibility, suitable mechanical properties and biodegradability, with the possibilities provided by using additive manufacturing, to ultimately create a biodegradable orthopedic implant with patient-specific design.

Firstly, the mechanical properties of magnesium are much closer to that of the human bone compared to other metals used in orthopedic implants, such as stainless steel and titanium. This allows for magnesium alloys to be used in load bearing implants, but may also prevent common problems related to other metallic implants, such as stress shielding.

Secondly, magnesium is biodegradable. This means that the implant will degrade over time, ideally at the same rate as the bone regenerates. This would permit a decreased risk of periprosthetic infections and facilitate the treatment of younger patients who are still growing. It would also mean avoiding a second surgery in order to remove the implant, often related to a higher risk of patient morbidity.

Finally, by investigating the incorporation of different alloying elements into magnesium powders, we want to develop a biodegradable magnesium alloy suitable for additive manufacturing, and thus make it possible for the creation of biodegradable patient-specific orthopedic implants.

Contact: Hanna Nilsson Åhman (hanna.nilsson-ahman@swerim.se)

Additive manufacturing, or 3D-printing, has opened up new possibilities from both a component design perspective and also for the development of new materials, since new microstructural combinations can be created through the use of processing conditions very different to traditional manufacturing. In this project, which is part of the SwedNess graduate school providing research training in neutron scattering, we aim to use advanced neutron and synchrotron characterizations techniques to investigate the microstructural formation related to the additive manufacturing process, and their connection to the resulting mechanical properties.

The project is focused primarily on biodegradable magnesium alloys as they can allow for temporary fixation of for example bone fractures, eliminating the need for a second surgery to remove the implant. A degradable material also decreases the risk for infection over time, since bacteria attach to dead material, like implants. These aspects are very important to consider, bearing in mind the growing antibiotic resistance worldwide.

In particular, for fracture fixation applications, adequate mechanical properties are crucial, and for degradable materials, the degradation rate needs to be adjusted to the growth rate of the patient’s own tissue. A thorough understanding of the mechanical properties related to the material processing and its microstructure is therefore of highest importance.

This project aim is to gain an in-depth understanding of microstructure formation by extensive characterization of novel magnesium alloys at all relevant length scales, as well as an understanding of the resulting mechanical properties. By experimental and numerical characterization, we expect to provide new knowledge on the possibilities and limitations of 3D-printable magnesium-based alloys.