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T. Balusamy et al.
surface layer provides suitable surface properties while the coarse-grained matrix
provides the ductility. SMAT provides desirable surface topography and increases
the average surface roughness. The surface topography of materials determines its
hydrophilic or hydrophobic nature. For implants, a hydrophilic surface is considered
to be more desirable than a hydrophobic one because of its better interaction with
biological fluids, cells, and tissues. In addition, generating the desired surface topography could provide significant enhancement in osteoblast adhesion, proliferation,
maturation, and mineralization. SMAT decreases the grain size, induces compressive residual stress, microstrain, defects/dislocations, and phase transformation, all
of which enable a significant improvement in hardness, fatigue resistance, and tribological properties of materials. In addition, the extent of grain refinement, extent of
deformation, extent of change in surface roughness, phase transformation, residual
stress, microstrain, and defect/dislocation density could influence the performance of
materials subjected to SMAT. This could ultimately influence the biological performance of the implant materials. The present chapter aims to provide detailed coverage
of SMAT of stainless steel, Ti alloys, Ni-Ti alloy, CoCrMo alloy, and how the nanostructured surface enables an improvement in the characteristic properties that are
suitable for biomedical applications.
Keywords Metallic biomaterials · Surface nanocrystallization · Surface
mechanical attrition treatment · Mechanical properties · Corrosion · Cell response
1 Surface Nanostructuring by Surface Mechanical
Attrition Treatment
Nanostructured materials have received considerable attention due to their unique
physical, chemical, and mechanical properties that are appropriate for numerous
technological applications. Recently, nano/ultrafine-grained materials produced by
severe plastic deformation (SPD) have gained much importance in biomedical applications. Bulk nanostructured materials can be produced by methods such as equal
channel angular pressing, accumulative roll bonding, high-pressure torsion, multiple
compression, etc. However, the ductility of materials produced by these methods is
significantly low when compared to the coarse-grained materials. Surface mechanical
attrition treatment (SMAT) is a surface severe plastic deformation (S
2 PD) method
that enables the formation of a nanostructured surface layer on metallic materials and improves the overall properties and performance, without affecting their
inherent properties [1–5]. The amount of plastic working energy incurred during
treatment is relatively much less for S
2 PD than bulk deformation. High strength
materials like stainless steels and titanium alloys can be easily processed by SMAT
whereas processing them with equal channel angular pressing requires a larger load
and specially designed dies. Other advantages of SMAT include high throughput
processing and the ability to process materials at a lower cost.
T. Balusamy et al.
surface layer provides suitable surface properties while the coarse-grained matrix
provides the ductility. SMAT provides desirable surface topography and increases
the average surface roughness. The surface topography of materials determines its
hydrophilic or hydrophobic nature. For implants, a hydrophilic surface is considered
to be more desirable than a hydrophobic one because of its better interaction with
biological fluids, cells, and tissues. In addition, generating the desired surface topography could provide significant enhancement in osteoblast adhesion, proliferation,
maturation, and mineralization. SMAT decreases the grain size, induces compressive residual stress, microstrain, defects/dislocations, and phase transformation, all
of which enable a significant improvement in hardness, fatigue resistance, and tribological properties of materials. In addition, the extent of grain refinement, extent of
deformation, extent of change in surface roughness, phase transformation, residual
stress, microstrain, and defect/dislocation density could influence the performance of
materials subjected to SMAT. This could ultimately influence the biological performance of the implant materials. The present chapter aims to provide detailed coverage
of SMAT of stainless steel, Ti alloys, Ni-Ti alloy, CoCrMo alloy, and how the nanostructured surface enables an improvement in the characteristic properties that are
suitable for biomedical applications.
Keywords Metallic biomaterials · Surface nanocrystallization · Surface
mechanical attrition treatment · Mechanical properties · Corrosion · Cell response
1 Surface Nanostructuring by Surface Mechanical
Attrition Treatment
Nanostructured materials have received considerable attention due to their unique
physical, chemical, and mechanical properties that are appropriate for numerous
technological applications. Recently, nano/ultrafine-grained materials produced by
severe plastic deformation (SPD) have gained much importance in biomedical applications. Bulk nanostructured materials can be produced by methods such as equal
channel angular pressing, accumulative roll bonding, high-pressure torsion, multiple
compression, etc. However, the ductility of materials produced by these methods is
significantly low when compared to the coarse-grained materials. Surface mechanical
attrition treatment (SMAT) is a surface severe plastic deformation (S
2 PD) method
that enables the formation of a nanostructured surface layer on metallic materials and improves the overall properties and performance, without affecting their
inherent properties [1–5]. The amount of plastic working energy incurred during
treatment is relatively much less for S
2 PD than bulk deformation. High strength
materials like stainless steels and titanium alloys can be easily processed by SMAT
whereas processing them with equal channel angular pressing requires a larger load
and specially designed dies. Other advantages of SMAT include high throughput
processing and the ability to process materials at a lower cost.