Division of the hardness of molybdenum into rate-dependent and rate-independent components

Stone, Donald S.; Yoder, Karl

doi:10.1557/jmr.1994.2524

Cited by 71 publications

(44 citation statements)

References 10 publications

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“…This value also compares favorably with the activation energy for viscous flow of 535 kJ/mol. Stone and Yoder [18] also used an indentation system, capable of operating in the 160 to 298 K temperature range, to investigate the rate-dependent and rate-independent components of the hardness of Mo. They found activation volumes for Mo in agreement with those reported in the literature, given the 50 pct typical scatter in these type of data.…”

Section: B Effect Of Temperature (Activation Energy For Creep)supporting

confidence: 58%

Indentation power-law creep of high-purity indium

Lucas

Oliver

1999

Metall Mater Trans A

589

240

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Using a variety of depth-sensing indentation techniques, the creep response of high-purity indium, from room temperature to 75 ЊC, was measured. The dependence of the hardness on the variables of indentation strain rate (stress exponent for creep (n)) and temperature (apparent activation energy for creep (Q)) and the existence of a steady-state behavior in an indentation test with a Berkovich indenter were investigated. It was shown for the first time that the indentation strain rate ( /h) could ⅐ h be held constant during an experiment using a Berkovich indenter, by maintaining the loading rate divided by the load ( /P) constant. The apparent activation energy for indentation creep was found ⅐ P to be 78 kJ/mol, in accord with the activation energy for self-diffusion in the material. Finally, by performing /P change experiments, it was shown that a steady-state path independent of hardness ⅐ P could be reached in an indentation test with a geometrically similar indenter.

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Section: B Effect Of Temperature (Activation Energy For Creep)supporting

confidence: 58%

Indentation power-law creep of high-purity indium

Lucas

Oliver

1999

Metall Mater Trans A

589

240

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“…(63) and (67)): hardness decreases with increasing indentation depth or load [203,213]. It has also been demonstrated recently by Lucas and Oliver [203] that, in constant _ F=F experiments, the indentation strain-rate reaches a ''steady state'' and is given by 0:5 _ F=F (Fig.…”

Section: Constant Loading Rate Over Load _mentioning

confidence: 55%

Scaling, dimensional analysis, and indentation measurements

Cheng

2004

Materials Science and Engineering: R: Reports

935

512

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We provide an overview of the basic concepts of scaling and dimensional analysis, followed by a review of some of the recent work on applying these concepts to modeling instrumented indentation measurements. Specifically, we examine conical and pyramidal indentation in elastic-plastic solids with power-law workhardening, in power-law creep solids, and in linear viscoelastic materials. We show that the scaling approach to indentation modeling provides new insights into several basic questions in instrumented indentation, including, what information is contained in the indentation load-displacement curves? How does hardness depend on the mechanical properties and indenter geometry? What are the factors determining piling-up and sinking-in of surface profiles around indents? Can stress-strain relationships be obtained from indentation load-displacement curves? How to measure time dependent mechanical properties from indentation? How to detect or confirm indentation size effects? The scaling approach also helps organize knowledge and provides a framework for bridging micro-and macroscales. We hope that this review will accomplish two purposes: (1) introducing the basic concepts of scaling and dimensional analysis to materials scientists and engineers, and (2) providing a better understanding of instrumented indentation measurements. # 2004 Published by Elsevier B.V.

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“…(i) the displacement excursion can end in an ''overshoot" which describes the mean pressure for continued plastic deformation under the indenter (Kramer et al, 1999;Kramer et al, 2001); (ii) there is a rate dependence, signifying the importance of dislocation dynamics (Moody et al, 1998;Stone and Yoder, 1994); (iii) the activation volume for plastic deformation associated with very small plastic zones and high dislocation densities may be quite small compared to bulk deformation processes in both polycrystalline solids (Asaro and Suresh, 2005) and single crystals (Schuh et al, 2005).…”

Section: Introductionmentioning

confidence: 99%