Processing and properties of a new biodegradable Mg−Zn−Ca−Zr alloy

Abstract

Magnesium alloys are used for degradable orthopaedic and cardiovascular implants due to their favourable mechanical and biological properties, degradation ability in physiological environment and stimulatory effect on the new bone formation. The research challenges are related to the increase of biological and mechanical compatibility. For the present study, a magnesium based alloy design was conducted to the following chemical composition: Mg−2.7Zn−1Ca−0.6Zr (wt.%). A complex thermomechanical processing route was applied: a plastic deformation by extrusion at various temperatures and deformation degrees (400 °C–480 °C, ϵ = 20 %–40 %), followed by various final heat treatments at 200 °C–400 °C for 10 min–60 min. Further, the influence of processing parameters upon the structure, mechanical properties and biological response was studied. Processed specimens were characterized by scanning electron microscopy (secondary electron imaging and energy dispersive spectroscopy) and mechanically by tensile tests. The most representative results were obtained for the samples extruded at 450 °C/ϵ = 20 %, followed by a final heat treatment at 350 °C/15 min, air cooling. Further, for samples which revealed promising results, in‐vitro testing was developed. Biocompatibility testing of the Mg−2.7Zn−1Ca−0.6Zr (wt.%) alloy was realized by indirect contact studies using the Vero (ATCC® CCL‐81™, American Type Culture Collection) cell line. Cells morphologies, cell viability and proliferation were evaluated.

Laser Powder Bed Fusion Applied to a New Biodegradable Mg-Zn-Zr-Ca Alloy

“…Apparently, gas atomization and mechanical alloying could both be suitable for this purpose, but in terms of resource consuming (materials and energy) on the entire processing chain, mechanical alloying is reported to be quite efficient and a low-cost modality for producing metallic powders with the above characteristics [ 25 ]. In addition, it should be considered that due to repeated fracturing and cold welding of the particles caused by severe plastic deformation, mechanical alloying leads to a powder material with a nano-crystalline structure even if the powder shape is not so regular and spherical as it is with gas atomization [ 26 , 27 , 28 ].…”