Degradable implants have been in use for bone surgery for decades. However, degradable
metal implants are one of the new research areas of biomaterials science. There is a potential for
application of degradable metal implants as screws and plates in bones. Magnesium alloys are one
of the new candidate materials for degradable implants. Magnesium has good biocompatibility due
to its low toxicity, and it is a corroding, i.e. dissolvable, metal. Furthermore, magnesium is needed
in human body, and naturally found in bone tissue. Mechanical properties of magnesium alloys are
dimensionally comparable to the cortical bone substance. In this study, corrosion behavior of
magnesium metal at the bone interface and the possibility of new bone cell formation have been
investigated. Cortical bone screws were machined from magnesium alloy AZ31 extruded rod and
implanted to hip-bones of sheep via surgery. Three months after surgery, the bone segments
carrying these screws were removed from the sacrificed animals. Samples were sectioned to reveal
Mg/bone interfaces and investigated using optical microscope, SEM-EDS and radiography. Optical
and SEM images showed that there was a significant amount of corrosion on the magnesium screw.
The elemental mapping results indicate, due to the presence of calcium and phosphorus elements,
that there exists new bone formation at the interface. From the results of this study, it may be stated
that the potential for using magnesium alloys as a bone implant material is expected to be
significant.
Titanium, zirconium and magnesium alloys are considered to be biocompatible, and can
be used as implants such as hip ball and sockets and to make medical equipments. Biomaterials
with hybrid structures in some applications utilizing the beneficial properties of different metals
together are considered potential implant materials. Therefore, in this study, experimental trials
were attempted to bond pure magnesium, AM60 (6 wt% Al-0.27 wt% Mn), and AZ31 (3 wt% Al-1
wt% Zn) alloys to pure zirconium and Ti6Al4V (6 wt% Al-4 wt% V) alloy to experimentally
evaluate the forming bimetallic structures by diffusion bonding technique by vacuum hot pressing.
SEM analysis showed the presence of a significant diffusion zone and a presence of diffusion
bonding in some metallic couples. It may be suggested that novel hybrid implant materials,
composed of diffusion couples of magnesium, zirconium and titanium alloys may emerge in the
future.
In this study, corrosion behaviour of magnesium AZ31 alloy sheets produced by different casting methods was investigated. Magnesium AZ31 sheets of 2 mm in thickness produced by conventional direct chill castingzrolling and AZ31 sheets of 2 mm in thickness and 1500 mm in width produced by twin roll strip castingzrolling were used as samples. For the determination of processing method dependent corrosion behaviour, potentiodynamic electrochemical corrosion and also immersion tests were performed in 0.5M Na 2 SO 4 and 0.01M NaCl solutions. Corrosion damage occurred during the tests was extensively investigated by scanning electron microscopy. Results of the work revealed the clear role of processing method dependent size and distribution of intermetallics on the corrosion behaviour of AZ31 sheets.
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