A different type of indentation size effect

Shim, Sang‐Chul; Bei, Hongbin; George, E.P.; Pharr, George M.

doi:10.1016/j.scriptamat.2008.07.026

Cited by 249 publications

(155 citation statements)

References 21 publications

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“…The MAX obtained using the blunt indenter is much smaller, only about 43 % of that from the sharp indenter. This difference in MAX is consistent with nanoindentation size effects reported by other researchers Shim et al, 2008). In those studies, the maximum shear stress under small spherical indenters at the first pop-in was found to be very high, on the order of the theoretical strength; for larger spheres, the maximum stress decreased with increasing indenter radius.…”

Section: Nanoindentation Experimentssupporting

confidence: 91%

Effect of the Spherical Indenter Tip Assumption on the Initial Plastic Yield Stress

Ma¹,

Levine²,

Dixson³

et al. 2012

Nanoindentation in Materials Science

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Section: Nanoindentation Experimentssupporting

confidence: 91%

Effect of the Spherical Indenter Tip Assumption on the Initial Plastic Yield Stress

Ma¹,

Levine²,

Dixson³

et al. 2012

Nanoindentation in Materials Science

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“…Figure 6d shows the stress-strain curves for SiC-6H(0001) extracted using the flow stress and characteristic strain values obtained from a combination of experimental indentation hardness values and FEA simulations using equivalent cones. The results from the FEA analysis shown in Figure 6d show similar trends to the results obtained by Shim et al [44] but the values of the Holloman fit exponents (n and K) and the yield strength are different due to the difference in the values of the modulus and hardness used by Shim et al [44]. The yield strength is estimated to be 6.2-8 GPa, which agrees with previous literature [4,41].…”

Section: Extraction Of Flow Propertiessupporting

confidence: 87%

“…[44] shown schematically in Figure S2 in Supplementary Materials, was used to perform FEA simulations to estimate the flow properties of SiC-6H in the <0001> direction. The friction coefficients of 0 and 0.2 were chosen to represent the ideal frictionless case and the realistic case for SiC-6H, respectively.…”

Section: Methodsmentioning

confidence: 99%

Fracture Toughness Evaluation and Plastic Behavior Law of a Single Crystal Silicon Carbide by Nanoindentation

2018

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Nanoindentation-based fracture toughness measurements of ceramic materials like silicon carbide (SiC) with pyramidal indenters are of significant interest in materials research. A majority of currently used fracture toughness models have been developed for Vickers indenters and are limited to specific crack geometries. The validity of the indentation-cracking method for the fracture toughness measurement of single crystal SiC, the elastic-plastic anisotropy and orientation dependence around the c-axis when indented in the <0001> direction is examined using nanoindentation with different pyramidal indenters. The residual impressions are analyzed using scanning electron microscopy to measure the crack lengths and the validity of existing fracture toughness measurement methods and equations is analyzed. A combination of nanoindentation with different pyramidal indenters to produce a wide range of effective strains and finite element simulation is used to extract flow properties of single crystal SiC in the <0001> direction. It is observed that there is no orientation dependence around the c-axis when SiC-6H is indented in the <0001> direction with a Berkovich indenter, i.e., it is transversely isotropic. It is also found that for a Berkovich indenter, the Jang and Pharr model, which is based on the Lawn model for cone/halfpenny cracks, gives approximately constant values at low loads (<1 N), while at higher loads (>1 N), the Laugier model gives constant fracture toughness values. Finite element analysis using equivalent cones is used along with measured hardness values to estimate the yield strength, the work hardening exponents and the stress-strain curve for single crystal SiC-6H in the <0001> direction.

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“…Plastic deformation in nanoscale volumes of materials often exhibits a stochastic, discontinuous character, in contrast to the typical smooth yield behavior in their bulk counterparts [1][2][3][4][5][6][7]. Such jerky behavior has been attributed to the instability of microscopic defect processes, such as dislocation nucleation or depinning in crystalline metals [8,9], phase transformation in semiconductors [10] and localized shear transformation in amorphous metals [11].…”

Section: Introductionmentioning

confidence: 99%