Effect of ECAP Processing on Corrosion Behavior and Mechanical Properties of the ZFW MP Magnesium Alloy as a Biodegradable Implant Material

• Published in: Advanced engineering materials 2018-10, Vol.20 (10), p.n/a
• Main Authors: Gholami‐Kermanshahi, Mozhgan, Neubert, Volkmar‐Dirk, Tavakoli, Mansour, Pastorek, Filip, Smola, Bohumil, Neubert, Volkmar
• Format: Article
• Language: English
• Subjects: biomaterial; ECAP processing; implant; Mg alloy
• ISSN: 1438-1656; 1527-2648
• DOI: 10.1002/adem.201800121

Equal channel angular pressing (ECAP) is used to investigate the influence of microstructural evolution on mechanical properties and corrosion resistance of an extruded Mg alloy (ZFW MP) via route BC at 579 K. The transmission electron microscope (TEM) and the optical microscope (OM) are used to observe the microstructure. Tensile testing and hardness measurement are used to investigate the mechanical properties at room temperature, and electrochemical impedance spectroscopy (EIS) and potentiodynamic measurements are used to examine the corrosion properties in Hank's solution at 37 °C. The ECAPed samples show the enhanced mechanical properties as compared with the extruded sample. The ECAPed ZFW MP alloy possesses a homogeneous microstructure due to dynamic recrystallization (DRX), as indicated by the resulting microstructures. However, the electrochemical measurements show that a reduction in the corrosion resistance is caused by the ECAP processing. A broader grain size distribution and a continuous network of the oxide layers along grain boundaries result in an improvement in the corrosion resistance in the extruded sample as compared with the ECAPed sample. However, better mechanical properties are observed with a further homogeneous microstructure in the ECAPed sample as compared with the extruded counterpart. The ECAPed Magnesium alloy with a homogenized microstructure and a narrow grain size distribution show better mechanical strength than the as‐extruded counterpart used as a degradable biomaterial in medical implants. The increase in strength is accompanied by a reduction in uniform corrosion resistance. However, the increase of ECAP pass number decreases the tendency toward localized corrosion.