NanoindentationLecture 2 Case Study

Do Kyung Kim

Department of Materials Science and EngineeringKAIST, Korea

Nano Ceramics Research Laboratory

Applications of nanoindentation

• Mechanical characterization of nanostructures

• Pressure-induced phase transformation

• Thin film and MEMS structure – mechanical properties

• Biomechanics

• Newly Developed Technique

Mechanical Characterization of Nanostructures

Nano Ceramics Research Laboratory

Carbon Nanotube (1)

• Vertically aligned carbon nanotubes were prepared using PECVD method with different nickel catalyst thickness.

• The nanoindentation on a VACNT forest consecutively bends nanotubes during the penetration of the indenter.

Sample ASample A Sample BSample B

Sample CSample C

Gleason, J Mech Phys Solids, 2003

Nano Ceramics Research Laboratory

Carbon Nanotube (2)

• The resistance of a VACNT forest to penetration is due to successive bending of nanotubes as the indenter encounters nanotubes

• Superposition of interaction between the indenter and nanotubes encountered by the indenter during nanoindentation gives the total penetration resistance.

Gleason, J Mech Phys Solids, 2003

Nano Ceramics Research Laboratory

Carbon Nanotube (2)

• Average f-p curve for the three samples from experiements

• Sample C (high density, small length)Sample A, B (Same density)Sample A (Larger diameter and smaller length)

Gleason, J Mech Phys Solids, 2003

Nano Ceramics Research Laboratory

Silver Nanowire (1)

• Silver nanowire-not single crystal but twinned-prepared from two silver solutions (AgNO3 and NaOH) and adhered onto glass slide.

• Nanoindentation and imaging with same Berkovich indenter.• Penetration depth as low as 15 nm. (30 % of diameter)

Caswell, Nano Letters, 2003

Nano Ceramics Research Laboratory

Silver Nanowire (2)

• Hardness 0.87 GPa / Elastic modulus 88 GPa• In good agreement with the nanoindentation value of bulk single crys

tal, 2 times higher than macroscale indentation results (indentation size effect)

• This approach permits the direct machining of nanowires.

Caswell, Nano Letters, 2003

Nano Ceramics Research Laboratory

ZnO and SnO2 nanobelt (1)

• The nanobelts were synthesized by thermal evaporation of oxide powder.

• Indentation with maximum 300 N with loading rate 10 N/s

Wang, APL, 2003

Nano Ceramics Research Laboratory

ZnO and SnO2 nanobelt (2)

• ZnO is a little softer than bulk single crystal.

• The crack propagates along [101] and cleavage surface is (010).

Wang, APL, 2003

Pressure-induced Phase Transformation

Nano Ceramics Research Laboratory

Silicon (1)

• Single crystal silicon undergoes phase transformation during indentation

• A sudden displacement discontinuity referred to as a pop-in

• Upon unloading, pop-out or kink pop-out happen, resulting from a sudden material expansion Gogotsi, J Mater Res, 2004

Nano Ceramics Research Laboratory

Silicon (2)

• The average pop-in pressure is determined from pure elastic loading assumption.

Gogotsi, J Mater Res, 2004

Nano Ceramics Research Laboratory

Silicon (3)

• Single and multiple pop-in events occurred during indentation• These events could be due to either subsurface cracking, squeezing

out of ductile materials or sudden dislocation burtst

1 mN/s 5 mN/s

Gogotsi, J Mater Res, 2004

Nano Ceramics Research Laboratory

Silicon (4)

• A great amount of a-Si, Si-III, or Si-XII is at deeper rather than shallower depths for a number of unloading conditions.

• The results from different wavelength spectrum show a-Si, Si-III, or Si-XII exist below the surface.

• Pop-in, out Si-III or Si-XII and No pop-in, out a-SiGogotsi, J Mater Res, 2004

Nano Ceramics Research Laboratory

Germanium (1)

• Nanoindentation experiments were performed using Berkovich and cube-corner indenters

• The unloading pop-out or elbow phenomena was not observed in loading curve.

• A number of displacement discontinuities in the loading curve are caused by discontinuous crack extension and chipping.

Pharr, APL, 2005

Nano Ceramics Research Laboratory

Germanium (2)

• SEM observation of the cube corner hardness impressions revealed a thin layer of extruded material.

• The micro-Raman spectra for cube-corner indentation exhibits distinct narrow Ge-IV and a-Ge peaks.

• Ge-IV phased vanishes within 20 hours of removing pressure.

Pharr, APL, 2005

Thin Film and MEMS Structure – Mechanical Properties

Nano Ceramics Research Laboratory

MEMS structure (1)

• Silicon nanobeam fabricated by micromachining process

• Load applied by indentation loading machine

• Si strength-17.6 GPa (bulk single crystal strength 6 GPa)

• Similar elastic modulus

Li, Ultramicroscopy, 2003

Nano Ceramics Research Laboratory

MEMS structure (2)

• SiO2 microbeam fabrication by micromachining process• SiO2 strength 68 Gpa (18.5 m sample) / 2.5 Gpa (58.5 m sample)

Lee, J Kor Ceram Soc, 2003

Nano Ceramics Research Laboratory

Thin films – Al (1)

• Aluminum single crystal (111) showing pop-in behavior• The maximum critical load 22 N a mean pressure 14.7 GPa whic

h is equivalent to a simplified estimate of the theoritical shear stress.• Dislocation is responsible for pop-in events.

Moris Jr, J Mater Res, 2004

Nano Ceramics Research Laboratory

Thin films – Al (2)

• In situ nanoindentation • Approach Contact Plastic deformation Extensive dislocation activity

Moris Jr, J Mater Res, 2004

Nano Ceramics Research Laboratory

Thin films – Al (3)

Before indentation

After indentation with same direction

After indentation with tilted direction(dislocation in entire grain)

Moris Jr, J Mater Res, 2004

Nano Ceramics Research Laboratory

Residual stress (1)

• Residual stress from– non-uniform cooling down from the processing temperature– deposition of a surface coating or a thin film on a substrate

• Equal biaxial state of residual stress (tensile or compressive)

Suresh, Acta Mater, 1998

Nano Ceramics Research Laboratory

Residual stress (2)

• Tensile • Compressive

Suresh, Acta Mater, 1998

Nano Ceramics Research Laboratory

Residual stress (3)

• Implementationwith ref. sample

Suresh, Acta Mater, 1998

Nano Ceramics Research Laboratory

Superlattice (1)

• W/ZrN nanolayer• Superlattice period: 2.1 nm• Annealed at 1000 C for 1hr

• AlN/VN nanolayer• Epitaxial stabilization of B1-AlN• Transformation to wurtzite

Scott, MRS bulletin, 2003

• Nanscale multilayered coating

Nano Ceramics Research Laboratory

Superlattice (2)

• Nanoindentation TiN/TiB2 superlattice

Scott, MRS bulletin, 2003

Biomechanics

Nano Ceramics Research Laboratory

Dental hard tissue (1)

Anisotropic structure of enamel

Swain, J Mater Res, 2006

Nano Ceramics Research Laboratory

Dental hard tissue (1)

• Nanoindentation experiments on enamel with different orientation and indenter radius

• Parallel to enamel rods, the hardness and modulus are 3.9 Gpa and 87.5 GPa, respectively , whereas perpendicular to enamel rods, they are 3.3 GPa and 72.2 GPa.

Nano Ceramics Research Laboratory

Dental hard tissue (3)

• The bacterial demineralization in enamel known as caries is simply detected through the changes in its mechanical properties.

Nano Ceramics Research Laboratory

Dental hard tissue (4)

LingualBuccal

Pulp

Dentin

Hardness (GPa)

2.5

3

3.5

4.0

4.5

5

5.5

6 LingualBuccal

Pulp

Dentin

Elastic Modulus (GPa)

110

100

90

80

70

60

50

120

Weihs, Archives of Oral Biology, 2002

Nanoindentation mapping of enamel tooth structure

Nano Ceramics Research Laboratory

Human bone (1)

• Human Femur – cortical and trabecula bone lamellae

Goldstein, J Biomech, 1999

Nano Ceramics Research Laboratory

Human bone (2)

• The mean elastic modulus was found to be significantly influenced by the type of lamella and by donor.

• Hardness followed a similar distribution as elastic modulus among types of lamellae and donor.

Goldstein, J Biomech, 1999

Nano Ceramics Research Laboratory

Biocomposite (1)

• Hydroxyapatite (HA) + polymethylmethacrylate (PMMA) + co-polymer coupling agent

• In vitro interfacial mechanics of HA and PMMA cross section of the composite

• Microscopic analysis• Indentation analysis (load-displacement curve) more comprehensi

ve local analysis• In vitro testing – a reduction of bulk bending, local elastic modulus, l

ocal hardness with increase of immersion time• The effect of coupling agent improvement of the interfacial mecha

nics

Marcolongo, IEEE Bioeng, 2004

Nano Ceramics Research Laboratory

Biocomposite (2)

• Human bone– 45-60% mineral: HA– 20-30% matrix:

collagen– 10-20% water

Marcolongo, IEEE Bioeng, 2004

Nano Ceramics Research Laboratory

Biocomposite (3)

• To determine the local mechanical properties of a bioactive composite a function of immersion period in simulated body fluid (SBF) in vitro testing

Marcolongo, IEEE Bioeng, 2004

Nano Ceramics Research Laboratory

Biocomposite (4)

• The “in vitro” local mechanical properties of the bioactive composite as a function of surface bioactivity

Marcolongo, IEEE Bioeng, 2004

Newly Developed Technique

Nano Ceramics Research Laboratory

Cross-section of indentation damage(1)

• Focused ion beam TEM sample preparation

Indentation Pt Fast mill

Tilt Markers Slow mill

Lift-off

Bradby, 2004

Nano Ceramics Research Laboratory

Cross-section of indentation damage(2) Fast unloading Slow unloading

Slip line

Misc. defect

Extended defect

Bradby, 2004

Silicon

Nano Ceramics Research Laboratory

Cross-section of indentation damage(3)

GaAs

InP

Bradby, 2004

Nano Ceramics Research Laboratory

Cross-section of indentation damage(4)

GaN

ZnO

Bradby, 2004

Nano Ceramics Research Laboratory

In-situ nanoindentation in SEM (1)

Utke, 2006

Nano Ceramics Research Laboratory

In-situ nanoindentation in SEM (2)

• Vitreloy 105 (Zr52.5Cu17.9Ni14.6Al10Ti5)

Partial correlation between shear band formation and displacement burst in P-h curve.

Utke, 2006

Nano Ceramics Research Laboratory

In-situ nanoindentation in SEM (3)

• FEB deposited reference pattern for in situ measure of contact area

Utke, 2006

Nano Ceramics Research Laboratory

In-situ nanoindentation in SEM (4)

Silicon pillar

Median crack Basal crack Buckling

Utke, 2006

Nano Ceramics Research Laboratory

In-situ nanoindentation in TEM (1)

Minor, 2002

Nano Ceramics Research Laboratory

In-situ nanoindentation in TEM (2)

Minor, 2002

Nano Ceramics Research Laboratory

In-situ nanoindentation in TEM (3)

Before After

Minor, 2002

Nano Ceramics Research Laboratory

Concluding remarks

• Broad applications of Nanoindentation to investigate the mechanical properties!!!