Magnesium alloys are promising materials for biodegradable implants due to their biocompatibility and their mechanical properties that are close to those of bones [1]. A magnesium alloy implant can give the necessary strength to a healing bone and afterwards degrade via corrosion inside the body. One advantage of such biodegradable implants is that no second surgery is needed to remove the implant after the bone has healed.

A main challenge with magnesium alloy implants is the correct adjustment of the corrosion rate [1]. An adjusted corrosion rate is important to give the bone the necessary support as long as it needs it before the degradation of the implant sets in. One way to influence the mechanical properties and the corrosion rate of magnesium alloys is to apply a severe plastic deformation (SPD) process in which the microstructure is transformed to obtain ultrafine grains [2].

In our research, the SPD process High Pressure Torsion Extrusion (HPTE) [3] is applied to the magnesium alloy ZK60 (Mg-Zn-Zr). Microstructural, mechanical, and corrosion properties are defined for the initial state of the ZK60 material and for the HPTE-processed state. In order to define these properties a variety of tests have been carried out. Microstructural changes have been elucidated using scanning and transmissional electron microscopy. The mechanical properties of the initial and processed states have been defined in quasistatic tensile tests and cyclic three point bending tests. Hydrogen evolution tests have been carried out to determine any changes in the corrosion rate.

In this presentation, an overview will be given of the recent results concerning changes in microstructural, mechanical, and corrosion properties between the initial state and the HPTE-processed state of the magnesium alloy ZK60.

References

[1] P. Chakraborty Banerjee, S. Al-Saadi, L. Choudhary, S.E. Harandi, R. Singh Materials, 2019, 12, 136.

[2] C. op’t Hoog, N. Birbilis, M.X. Zhang, Y. Estrin Key Engineering Materials, 2008, 384, 229-240.

[3] Y. Ivanisenko, R. Kulagin, V.Federov, A. Mazilkin, T. Scherer, B. Baretzky, H. Hahn Materials Science & Engineering A, 2016, 664, 247-256.