Correcting for contact area changes in nanoindentation using surface acoustic waves

Beck, Christian E.; Hofmann, Felix; Eliason, Jeffrey K.; Maznev, A. A.; Nelson, Keith A.; Armstrong, David E.J.

doi:10.1016/j.scriptamat.2016.09.037

Cited by 30 publications

(25 citation statements)

References 26 publications

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“…What our study has in common with the EMC 21) is that we consider the elastic modulus to be unchanged by irradiation. However, in the case of Heintze et al 22) the elastic modulus (219 GPa) and the measured indentation modulus E IT of unirradiated 9 mass% Cr F/M steel T91 was very stable over indentation depth and similar in magnitude. As will be shown later in Fig.…”

Section: Pile-up Corrected Hardnessmentioning

confidence: 87%

“…(3) of the elastic modulus of the indenter E I and the actual elastic modulus of the material E S , using E I = 1141 GPa, υ I = 0.07 11) for a diamond tip and E S = 410 GPa 11) , υ S = 0.28 for W. Therefore it can be said that E S is associated with the true projected area of contact including pile-up A P EMC . Note that the symbols used in this study as shown in the List of Symbols are somewhat different from those in the original works by S. I. Bulychev [28][29][30][31][32] , or as in Heintze et al 21) , Beck et al 22) and Hardie et al 23) Heintze et al s 21) pileup corrected hardness method, which can be called as the elastic modulus correction (EMC) method, was assessed on unirradiated, neutron irradiated and self-ion-irradiated 9 mass% Cr f/m steel T91. An advantage of the EMC 21) method is that one actually does not have to measure the pileup height, but can use the latter expression of H EMC in eq.…”

Section: Pile-up Corrected Hardnessmentioning

confidence: 97%

“…Based on the ndings by Sneddon 27) as well as later on by other researchers, Bulychev, Alekhin, Shorokov and their co-workers [28][29][30][31][32] , Heintze et al 21) , Beck et al 22) and Hardie et al 23) recently proposed different methods for pile-up corrected hardness. In eq.…”

Section: Pile-up Corrected Hardnessmentioning

confidence: 99%

“…(5) that only includes the square of the ratio of E EMC * to E*. Beck et al 22) also uses the elastic modulus expression, but they don t consider the elastic properties of the indenter in the modulus expressions. Further on, based on their 22) transient grating laser measurement results, they assumed that the elastic modulus of the specimen was changed after ion-irradiation.…”

Section: Pile-up Corrected Hardnessmentioning

confidence: 99%

“…Hence, the EMC method 21) is based on the assumption that the elastic modulus is independent of irradiation 21) . Beck et al 22) very recently proposed a method to correct NI-hardness of ion-irradiated (0.24 ± 0.02 dpa at 573 K) W-1mass%Re alloy. They introduced a correction factor C cor that re ected the difference in the actual elastic modulus between the ion-irradiated damaged layer and unirradiated material which were measured by transient grating laser measurements.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Evaluation of Ion-Irradiation Hardening of Tungsten Single Crystals by Nanoindentation Technique Considering Material Pile-Up Effect

et al. 2017

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Ion-irradiation hardening of pure tungsten (W) single crystal was evaluated by nanoindentation (NI) technique considering material pileup effect. Pure W single crystals of (001) surface orientation were ion-irradiated with 6.4 MeV Fe 3+ to 0.1 dpa, 1 dpa or 2 dpa at 573 K. The irradiation hardening was evaluated by means of NI measurements with elastic-modulus-based correction (EMC) method [C. Heintze et al.: J. Nucl. Mater. 472 (2016) 196-205]. The effect of material pile-up in tungsten was so signi cant that the bulk equivalent hardness values by EMC method were about 70% and 85% of uncorrected results for irradiated and unirradiated W(001), respectively. The ion-irradiation hardening values by EMC based method were approximately 40%, 50% and 60% of uncorrected results for 0.1 dpa, 1 dpa and 2 dpa, respectively. The measured maximum pile-up height was higher for irradiated W(001) than for unirradiated W(001) at each indentation depth. An averaged pileup height that was associated with the actual area of contact of pile up obtained from EMC hardness showed different responses to ion-irradiation depending on the indentation depth.

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Section: Pile-up Corrected Hardnessmentioning

confidence: 87%

Section: Pile-up Corrected Hardnessmentioning

confidence: 97%

Section: Pile-up Corrected Hardnessmentioning

confidence: 99%

Section: Pile-up Corrected Hardnessmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Evaluation of Ion-Irradiation Hardening of Tungsten Single Crystals by Nanoindentation Technique Considering Material Pile-Up Effect

et al. 2017

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Recent advances in characterising irradiation damage in tungsten for fusion power

Das

2019

SN Appl. Sci.

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Tungsten is the front-runner candidate for building the plasma-facing armour components for future fusion reactors. However, in-service irradiation by fusion-neutrons and helium will create lattice-defects in the material, compromising its properties and lifetime. Improving the component's resilience to radiation damage and accurately predicting the lifetime of irradiated components is key for commercial feasibility of the reactor. For this purpose, understanding the creation and evolution of radiation damage is essential. This paper reviews recent advances in characterising radiation damage through experimental and modelling techniques. Tungsten-ion-and helium-ion-implantation are commonly used to mimic the damage created by neutron-and helium-irradiation respectively. Defects (> 1.5 nm) can be directly imaged using transmission electron microscopy while all defects (size-independent), may be indirectly probed by measuring lattice strains induced by them (using diffraction techniques; synchrotron X-rays or high-resolution electron-backscatter). Neutron-irradiation produces mainly ½〈111〉 prismatic loops. Loop-interaction and structural organisation evolves with changing implantation dose and temperature. Helium-irradiation, < 573 K, induces formation of small helium-vacancy clusters, which evolve into bubbles, blisters and "fuzz" structure with changing temperature and dose. Nano-indentation or micro-cantilever bending tests can be used to examine mechanical properties of ion-implanted layers. Both heliumand neutron-implantation defects induce increased hardening often followed by subsequent strain-softening and localised deformation. Such irradiation-induced alterations are detrimental to material ductility and long-term structural integrity of tungsten-based components. Development of physically-based material models that capture the physics of underlying irradiation-induced changes, inspire confidence of reliably using simulations to predict mechanical behaviour and in-service performance of irradiated engineering components in future.

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Nanoscale lattice strains in self-ion implanted tungsten

Phillips

Das

et al. 2020

Acta Materialia

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Developing a comprehensive understanding of the modification of material properties by neutron irradiation is important for the design of future fission and fusion power reactors. Self-ion implantation is commonly used to mimic neutron irradiation damage, however an interesting question concerns the effect of ion energy on the resulting damage structures. The reduction in the thickness of the implanted layer as the implantation energy is reduced results in the significant quandary: Does one attempt to match the primary knock-on atom energy produced during neutron irradiation or implant at a much higher energy, such that a thicker damage layer is produced? Here we address this question by measuring the full strain tensor for two ion implantation energies, 2 MeV and 20 MeV in self-ion implanted tungsten, a critical material for the first wall and divertor of fusion reactors. A comparison of 2 MeV and 20 MeV implanted samples is shown to result in similar lattice swelling. Multi-reflection Bragg coherent diffractive imaging (MBCDI) shows that implantation induced strain is in fact heterogeneous at the nanoscale, suggesting that there is a non-uniform distribution of defects, an observation that is not fully captured by micro-beam Laue diffraction. At the surface, MBCDI and high-resolution electron back-scattered diffraction (HR-EBSD) strain measurements agree quite well in terms of this clustering/non-uniformity of the strain distribution. However, MBCDI reveals that the heterogeneity at greater depths in the sample is much larger than at the surface. This combination of techniques provides a powerful 1

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Correcting for contact area changes in nanoindentation using surface acoustic waves

Cited by 30 publications

References 26 publications

Evaluation of Ion-Irradiation Hardening of Tungsten Single Crystals by Nanoindentation Technique Considering Material Pile-Up Effect

Evaluation of Ion-Irradiation Hardening of Tungsten Single Crystals by Nanoindentation Technique Considering Material Pile-Up Effect

Recent advances in characterising irradiation damage in tungsten for fusion power

Nanoscale lattice strains in self-ion implanted tungsten

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