Laser Induced Micro/Nano …
447
Laser surface melting of AZ91D alloy resulted in a uniform distribution of the
β-Mg 17 Al 12 phase in the melted layer and the variation in scanning speed affected the
melted layer properties. In the case of higher scan speeds such as 20 and 30 mm/s, the
thermal-stress induced cracks have appeared, however, at lower scanning speeds such
as 5 and 10 mm/s such cracks were not noticed, thereby exhibiting better corrosion
resistance in the modified simulated body fluid solution [44]. The presence of refined
microstructure with the uniform distribution of the second phase leads to uniform
corrosion compared to the coarse microstructure which gives preferential sites for
localized attacks for the as-received alloy.
Laser surface treatments of Zn based alloys have not been extensively investigated
and research interests are kept growing to utilize the laser treatments to enhance the
mechanical properties and corrosion resistance of Zn based alloys [45–47]. Recently
laser surface remelting was carried out on Zn-0.5wt% Zr alloy and the as-cast alloy
has mainly consisted of the Zn 22 Zr phase [48]. The melted depth of the alloy in Ar
gas protection was about 300 μm and the surface layer was consisted of equiaxed
dendrites with a size of about 5-10 μm, besides the Zn 22 Zr phase was also dissolved
and the microhardness value of the melted layer was about 90 ~ 110 HV 0.025 . The
i corr value of the laser surface remelted alloy was about 3 times lower compared to
the as-cast alloy and about 137 mV positive shift in the corrosion potential was also
noticed in simulated body fluid solution indicating the better corrosion resistance of
the laser remelted surfaces.
2.4 Laser Surface Patterning
Engineering of the surface of metallic implants is focused in recent research to
improve implant performance such as rapid integration with supporting hard tissues,
retain mechanical integrity, enhance the biomineralization process, and speedy
recovery [49]. Titanium-based alloys, in particular, Ti64 is one of the metallic implant
materials generally used for dental and hip joint replacements owing to its excellent
fracture toughness, fatigue resistance, and Young’s modulus close to that of the
natural bone [50]. Consistent research works are in progress to produce micro/nano
textures on Ti-based alloys to enhance their in vitro performances. Laser patterning is
carried out to produce biomimetic textures that could respond to the living cells based
on the size and shape of the micro/nano textures. The control of laser parameters
during the direct laser patterning process could be able to fabricate various textures
such as micro/nano grooves, cubes, wells, etc. suitable for enhancing cell adhesion
and proliferation.
447
Laser surface melting of AZ91D alloy resulted in a uniform distribution of the
β-Mg 17 Al 12 phase in the melted layer and the variation in scanning speed affected the
melted layer properties. In the case of higher scan speeds such as 20 and 30 mm/s, the
thermal-stress induced cracks have appeared, however, at lower scanning speeds such
as 5 and 10 mm/s such cracks were not noticed, thereby exhibiting better corrosion
resistance in the modified simulated body fluid solution [44]. The presence of refined
microstructure with the uniform distribution of the second phase leads to uniform
corrosion compared to the coarse microstructure which gives preferential sites for
localized attacks for the as-received alloy.
Laser surface treatments of Zn based alloys have not been extensively investigated
and research interests are kept growing to utilize the laser treatments to enhance the
mechanical properties and corrosion resistance of Zn based alloys [45–47]. Recently
laser surface remelting was carried out on Zn-0.5wt% Zr alloy and the as-cast alloy
has mainly consisted of the Zn 22 Zr phase [48]. The melted depth of the alloy in Ar
gas protection was about 300 μm and the surface layer was consisted of equiaxed
dendrites with a size of about 5-10 μm, besides the Zn 22 Zr phase was also dissolved
and the microhardness value of the melted layer was about 90 ~ 110 HV 0.025 . The
i corr value of the laser surface remelted alloy was about 3 times lower compared to
the as-cast alloy and about 137 mV positive shift in the corrosion potential was also
noticed in simulated body fluid solution indicating the better corrosion resistance of
the laser remelted surfaces.
2.4 Laser Surface Patterning
Engineering of the surface of metallic implants is focused in recent research to
improve implant performance such as rapid integration with supporting hard tissues,
retain mechanical integrity, enhance the biomineralization process, and speedy
recovery [49]. Titanium-based alloys, in particular, Ti64 is one of the metallic implant
materials generally used for dental and hip joint replacements owing to its excellent
fracture toughness, fatigue resistance, and Young’s modulus close to that of the
natural bone [50]. Consistent research works are in progress to produce micro/nano
textures on Ti-based alloys to enhance their in vitro performances. Laser patterning is
carried out to produce biomimetic textures that could respond to the living cells based
on the size and shape of the micro/nano textures. The control of laser parameters
during the direct laser patterning process could be able to fabricate various textures
such as micro/nano grooves, cubes, wells, etc. suitable for enhancing cell adhesion
and proliferation.