Magnesium (Mg)-based bone implants degrade rapidly in the physiological
environment of the human body which affects their structural integrity
and biocompatibility before adequate bone repair. Rare earth elements
(REEs) have demonstrated their effectiveness in tailoring the corrosion
and mechanical behavior of Mg alloys. This study methodically
investigated the impacts of scandium (Sc) and terbium (Tb) in tailoring
the corrosion resistance, mechanical properties, and biocompatibility of
Mg–0.5Zn–0.35Zr–0.15Mn (MZZM) alloys fabricated via casting and hot
extrusion. Results indicate that addition of Sc and Tb improved the
strength of MZZM alloys via grain size reduction and solid solution
strengthening mechanisms. The extruded MZZM–(1–2)Sc–(1–2)Tb (wt.%)
alloys exhibit compressive strengths within the range of 336–405 MPa,
surpassing the minimum required strength of 200 MPa for bone implants by
a significant margin. Potentiodynamic polarization tests revealed low
corrosion rates of as–cast MZZM (0.25 mm/y), MZZM–2Tb (0.45 mm/y),
MZZM–1Sc–1Tb (0.18 mm/y), and MZZM–1Sc–2Tb (0.64 mm/y), and extruded
MZZM (0.17 mm/y), MZZM–1Sc (0.15 mm/y), MZZM-2Sc (0.45 mm/y), MZZM-1Tb
(0.17 mm/y), MZZM-2Tb (0.10 mm/y), MZZM–1Sc-1Tb (0.14 mm/y),
MZZM-1Sc-2Tb (0.40 mm/y), and MZZM–2Sc–2Tb (0.51 mm/y) alloys, which
were found lower compared to corrosion rate of high-purity Mg (∼1.0
mm/y) reported in the literature. Furthermore, addition of Sc, or Tb, or
Sc and Tb to MZZM alloys did not adversely affect the viability of
SaOS2 cells, but enhanced their initial cell attachment, proliferation,
and spreading shown via polygonal shapes and filipodia. This study
emphasizes the benefits of incorporating Sc and Tb elements in MZZM
alloys, as they effectively enhance corrosion resistance, mechanical
properties, and biocompatibility simultaneously.
Keywords
Corrosion property;In vitro cytotoxicity;Magnesium alloys;Mechanical property;Rare earth elements
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