Nanoindentation: Localized Probes of Mechanical Behavior of Materials

Bahr, David F.; Morris, Dylan J.

doi:10.1007/978-0-387-30877-7_16

Cited by 16 publications

(9 citation statements)

References 93 publications

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“…The increased propensity for pile-up fo deformed state is attributed to a lower strain hardening rate of the formed material [8]. Table 4 presents tensile test data in terms of the yield stress, the ultimate tensile strength and the final strength of the material, alongside the hardness predicted from the final strength, according to Tabor's Equation (4). Here the final strength is defined as the force at rupture divided by the rupture cross-section as measured after the test.…”

Section: Relation Between Mechanical Properties From Tensile Tests and Hardness Measurementsmentioning

confidence: 99%

“…At these scales, the understanding of the dislocation mechanisms acting during indentation and their interaction with the specimen’s surface is key to comprehending the mechanical response of the material [ 1 , 2 , 3 ]. Continuous improvements in methodologies to record and analyse load—displacement curves are promoting nanoindentation to complement conventional mechanical testing in materials selection and design [ 4 ]. Furthermore, the technique allows probing of positions with varying properties, for instance, across the thickness of a larger component.…”

Section: Introductionmentioning

confidence: 99%

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Depth-Sensing Hardness Measurements to Probe Hardening Behaviour and Dynamic Strain Ageing Effects of Iron during Tensile Pre-Deformation

et al. 2020

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This work reports results from quasi-static nanoindentation measurements of iron, in the un-strained state and subjected to 15% tensile pre-straining at room temperature, 125 °C and 300 °C, in order to extract room temperature hardness and elastic modulus as a function of indentation depth. The material is found to exhibit increased disposition for pile-up formation due to the pre-straining, affecting the evaluation of the mechanical properties of the material. Nanoindentation data obtained with and without pre-straining are compared with bulk tensile properties derived from the tensile pre-straining tests at various temperatures. A significant mismatch between the hardness of the material and the tensile test results is observed and attributed to increased pile-up behaviour of the material after pre-straining, as evidenced by atomic force microscopy. The observations can be quantitatively reconciled by an elastic modulus correction applied to the nanoindentation data, and the remaining discrepancies explained by taking into account that strain hardening behaviour and nano-hardness results are closely affected by dynamic strain ageing caused by carbon interstitial impurities, which is clearly manifested at the intermediate temperature of 125 °C.

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Section: Relation Between Mechanical Properties From Tensile Tests and Hardness Measurementsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Depth-Sensing Hardness Measurements to Probe Hardening Behaviour and Dynamic Strain Ageing Effects of Iron during Tensile Pre-Deformation

et al. 2020

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“…The plastic volume assuming a plastic volume radius to contact radius ratio of 2.12 following the analysis of Harvey is given for comparison. 38,39 The testing regime was designed to sample to various depths within a constrained area of the specimen. As such, each indent pattern was arranged within a grid cell that was 44 lm on a side (1936 lm 2 ).…”

Section: Experiments Detailsmentioning

confidence: 99%

“…Such spacing is required to eliminate effects from neighboring indents. 37,38 The effective contact radius in Table I is calculated from the fitted area function for the tip, with the triangular contact area being converted to an equivalent circle. The plastic volume assuming a plastic volume radius to contact radius ratio of 2.12 following the analysis of Harvey is given for comparison.…”

Section: Experiments Detailsmentioning

confidence: 99%

Variation in the nanoindentation hardness of platinum

Maughan¹,

Zbib

Bahr³

2013

J. Mater. Res.

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Pure platinum was probed with a nanoindenter fitted with a Berkovich tip to various depths. The indent pattern was made on the as-polished specimen prior to heat treating, after heat treating at 500°C for 30 min, and again after further heat treating at 1000°C for 30 min. The variability in the measured hardness decreased as the indentation depth increased from 50 to 300 nm. When the sampled was annealed, the hardness variation was also greater. Increasing hardness variation with decreasing dislocation density and sampling volume indicates that dislocation density plays a critical role in the observed variation, beyond solely instrumentation uncertainty, and supports a defect-based explanation for the stochastic behavior. It appears that the stochastic behavior occurs when multiple dislocations are present in the sampled volume rather than sampling only a single dislocation.

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“…The differences between the two measurements, one from nanoindentation and one from the measurement of the strain field from ECCI, could be due to a number of reasons. While the use of the expanding cavity model is justified for a Berkovich indenter used in a nanoindentation experiment (Kramer et al, 1998), issues with specimen pile-up or sink-in around an indenter are known to affect measurements with an expanding cavity model (Bahr & Morris, 2008) and, in fact, some researchers have attempted to develop new expanding cavity models that take into account material pile-up or sink-in effects (Hernot & Bartier, 2012). In our case, pile-up height was measured and when accounted for, the hardness measured from nanoindentation was recalculated to be 1.8 GPa.…”

Section: Resultsmentioning

confidence: 99%

Electron Channeling Contrast Imaging of Plastic Deformation Induced by Indentation in Polycrystalline Nickel

et al. 2013

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Vickers microindentation and Berkovich nanoindentation tests were carried out on a polycrystalline nickel (Ni) bulk specimen. Electron channeling contrast imaging (ECCI) in conjunction with electron backscattered diffraction was used to image and characterize plastic deformation inside and around the indents using a field emission scanning electron microscope. The ECCI was performed with a 5 keV beam energy and 0° tilt specimen position. The strain field distribution, slip lines, and Taylor lattices were imaged on an indented surface. Orientation mapping was used to investigate the local crystallographic misorientation and identify specific ⟨110⟩ slip systems. An ion milling surface preparation technique was used to remove materials from the surface which permitted the study of deformed microstructure below the indent. A dislocation density of 1011 cm-2 was calculated based on the curvature of bend contours observed in the ECCI micrographs obtained from the Vickers indents. A yield strength of 500 MPa was calculated based on the size of the strain field measured from the ECCI micrographs of the nanoindents. The combination of ion milling, ECCI, and electron backscattered diffraction was shown to be beneficial to investigate the indentation-induced plastic deformation in a polycrystalline Ni bulk specimen.

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Nanoindentation: Localized Probes of Mechanical Behavior of Materials

Cited by 16 publications

References 93 publications

Depth-Sensing Hardness Measurements to Probe Hardening Behaviour and Dynamic Strain Ageing Effects of Iron during Tensile Pre-Deformation

Depth-Sensing Hardness Measurements to Probe Hardening Behaviour and Dynamic Strain Ageing Effects of Iron during Tensile Pre-Deformation

Variation in the nanoindentation hardness of platinum

Electron Channeling Contrast Imaging of Plastic Deformation Induced by Indentation in Polycrystalline Nickel

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