Surface integrity of biodegradable Magnesium-Calcium orthopedic implant by burnishing

M. Salahshoor, Y. B. Guo

Research output: Contribution to journalArticlepeer-review

60 Scopus citations


Magnesium-Calcium (MgCa) alloy as an emerging biodegradable implant material has received considerable attention in orthopedic fixation applications. The biodegradable MgCa alloys avoid stress shielding and secondary surgery inherent with permanent metallic implant materials. They also provide sufficient mechanical strength in load carrying applications as opposed to biopolymers. However, the key issue facing a biodegradable MgCa implant is the fast corrosion in the human body environment. The ability to adjust the degradation rate of MgCa alloys is critical in the successful development of biodegradable orthopedic materials. Burnishing as a low plastic deformation process is a promising technique to tune surface integrity of MgCa implant surface for biodegradation control. However, the poor ductility of MgCa alloys imposes a great challenge for burnishing. This study focuses on the basic understanding of surface mechanical behavior of burnished biodegradable MgCa0.8 (wt%) alloy. The effects of burnishing parameters, i.e., pressure, feed, speed, number of path, and burnishing pattern on surface integrity factors such as surface topography, roughness, microhardness, microstructure, and residual stresses are investigated. The burnished surfaces are shinier and smoother than the as-machined ones. The MgCa alloy can be safely burnished at suitable burnishing conditions since no cracks are produced at the surface and in the subsurface. The microstructure including grain size does not show a noticeable change after burnishing. The machined surfaces are harder than the burnished ones down to the deep subsurface (~200 μm) as opposed to the shallow hardened depth (~50 μm) in cutting. Residual stresses are highly compressive especially at low burnishing pressure.

Original languageEnglish (US)
Pages (from-to)1888-1904
Number of pages17
JournalJournal of the Mechanical Behavior of Biomedical Materials
Issue number8
StatePublished - Nov 2011
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biomaterials
  • Biomedical Engineering
  • Mechanics of Materials


  • Biomaterial
  • Burnishing
  • Implant
  • Magnesium
  • Surface integrity


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