Effect of surface detection error due to elastic–plastic deformation on nanoindentation measurements of elastic modulus and hardness

Fulco, Sage; Wolf, Sarah; Jakes, Joseph E.; Fakhraai, Zahra; Turner, Kevin T.

doi:10.1557/s43578-021-00223-4

Cited by 7 publications

(9 citation statements)

References 31 publications

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“…41−43 Corrected values of the reduced modulus and hardness are obtained by modifying both indentation procedures and data analysis on the basis of our recently developed methods. 43 We find enhanced mechanical properties in the most stable glasses of these molecules (T dep ≈ 0.8T g ), on the order of 30−45% for hardness and 15−20% for reduced modulus, compared to those of glasses deposited at T g . Measurements over a broad range of deposition temperatures indicate that although the degree of enhancement correlates with the enhancement in density when T dep is close to T g , the enhancements in the modulus and hardness are beyond those predicted by density at low deposition temperatures (T dep < 0.8T g ).…”

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confidence: 72%

“…A procedure schematically shown in Figure 1D was adopted, which we have recently demonstrated can avoid surface detection errors. 43 This procedure can be summarized as follows:…”

Section: Methodsmentioning

confidence: 99%

“…Samples were prepared by physical vapor deposition and investigated by a modified nanoindentation approach. 43 More details can be found in the Materials and Methods section and Supporting Information (SI). Figure 2A,C shows examples of load versus displacement curves obtained for α,α− Phen, and α,α−A samples, respectively.…”

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confidence: 99%

“…The color gradient demonstrates the gradient of T dep values, and the patterns show points along the sample where nanoindentation was performed at room temperature. (D) Nanoindentation procedure at each point (approach, liftoff, lateral offset, and indentation) used to avoid surface detection errors 43.…”

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confidence: 99%

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Role of Molecular Layering in the Enhanced Mechanical Properties of Stable Glasses

Wolf

Fulco

Zhang

et al. 2022

J. Phys. Chem. Lett.

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The density, degree of molecular orientation, and molecular layering of vapor-deposited stable glasses (SGs) vary with substrate temperature (T dep ) below the glass-transition temperature (T g ). Density and orientation have been suggested to be factors influencing the mechanical properties of SGs. We perform nanoindentation on two molecules which differ by only a single substituent, allowing one molecule to adopt an in-plane orientation at low T dep . The reduced elastic modulus and hardness of both molecules show similar T dep dependences, with enhancements of 15−20% in reduced modulus and 30−45% in hardness at T dep ≈ 0.8T g , where the density of vapor-deposited films is enhanced by ∼1.4% compared to that of the liquid-quenched glass. At T dep < 0.8T g , one of the molecules produces highly unstable glasses with in-plane orientation. However, both systems show enhanced mechanics. Both the modulus and hardness correlate with the degree of layering, which is similar in both systems despite their variable stability. We suggest that nanoindentation performed normal to the film's surface is influenced by the tighter packing of the molecules in this direction.

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confidence: 72%

“…A procedure schematically shown in Figure 1D was adopted, which we have recently demonstrated can avoid surface detection errors. 43 This procedure can be summarized as follows:…”

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Role of Molecular Layering in the Enhanced Mechanical Properties of Stable Glasses

Wolf

Fulco

Zhang

et al. 2022

J. Phys. Chem. Lett.

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“…In 2002, it became the first and, to date, the only nanomechanical testing method sanctioned with an ISO norm (ISO:14,577 [7]). Still, a non-negligible number of the contributions to this focus issue are devoted to further improving its reliability [8][9][10][11][12][13], based on emerging technologies. These include more accurate imaging [8,10,11] and faster data processing [9], which, for example, allow for improved characterization of the geometry of the indenter tip and the resulting contact area.…”

Section: Nanoindentationmentioning

confidence: 99%