On extracting mechanical properties from nanoindentation at temperatures up to 1000 °C

Gibson, J. S.; Schröders, Sebastian; Zehnder, Christoffer; Korte‐Kerzel, Sandra

doi:10.1016/j.eml.2017.09.007

Cited by 49 publications

(18 citation statements)

References 60 publications

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“…Figure 3 subsequently displays the hardness and Young's modulus as determined by high-temperature nanoindentation. As has been done previously at very high indentation temperatures [29], the temperature-dependent Young's modulus and…”

Section: Resultssupporting

confidence: 61%

“…Therefore the degree of cracking or porosity need not be large to influence these measurements. [3], or due to errors in the Oliver-Pharr fit to the unloading data given there is creep deformation still present in the unloading curve ( Figure 4) that has been previously shown to result in low values of Young's modulus in high-temperature nanoindentation [29]. As mentioned, this fit assumes an entirely elastic unloading process, while the black arrow next to the curve clearly demonstrated this is not the case.…”

Section: Discussionmentioning

confidence: 73%

“…There are very little data on the mechanical properties of the material at the intended operating temperatures, as well as the mechanical properties of the criticallyimportant alumina and chromium carbide layers. Due to the recent advances in nano-mechanical testing, it is now possible to test these materials near the operating temperatures of the components[29][30][31], These MAX phase materials have been investigated in this work by hightemperature nanoindentation and micro-cantilever bending to measure the mechanical properties of the Al 2 O 3 and Cr 7 C 3 as well as the fracture toughness of the interfaces.…”

mentioning

confidence: 99%

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Mechanical characterisation of the protective Al2O3 scale in Cr2AlC MAX phases

Gibson

González‐Julián

Krishnan

et al. 2019

Journal of the European Ceramic Society

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MAX phases have great potential under demands of both high-temperature and high-stress performance, with their mixed atomic bonding producing the temperature and oxidation resistance of ceramics with the mechanical resilience of metals.Here, we measure the mechanical properties up to 980C by nanoindentation on highly dense and pure Cr2AlC, as well as after oxidation with a burner rig at 1200 • C for more than 29 hours. Only modest reductions in both hardness and modulus up to 980 • C were observed, implying no change in deformation mechanism. Furthermore, micro-cantilever fracture tests were carried out at the Cr2AlC/Cr7C3 and Cr7C3/Al2O3 interfaces after the oxidation of the Cr2AlC substrates with said burner rig. The values are typical of ceramic-ceramic interfaces, below 4 MPa √ m,leading to the hypothesis that the excellent macroscopic behaviour is due to a combination of low internal strain due to the match in thermal expansion coefficient as well as the convoluted interface.

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Section: Resultssupporting

confidence: 61%

Section: Discussionmentioning

confidence: 73%

mentioning

confidence: 99%

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Mechanical characterisation of the protective Al2O3 scale in Cr2AlC MAX phases

Gibson

González‐Julián

Krishnan

et al. 2019

Journal of the European Ceramic Society

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“…Image of spinel micropillar (left) adapted from Ref. 35 and plotted data taken from [I], [36] [II], [99] [III], [11] [IV], [100] [V]. [101] Images reprinted with permission by Elsevier from Ref.…”

Section: Prospective Articlementioning

confidence: 99%

Microcompression of brittle and anisotropic crystals: recent advances and current challenges in studying plasticity in hard materials

Korte‐Kerzel

2017

MRS Communications

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Recent years have seen an increased application of small-scale uniaxial testing-microcompression-to the study of plasticity in macroscopically brittle materials. By suppressing fast fracture, new insights into deformation mechanisms of more complex crystals have become available, which had previously been out of reach of experiments. Structurally complex intermetallics, metallic compounds, or oxides are commonly brittle, but in some cases extraordinary, though currently mostly unpredictable, mechanical properties are found. This paper aims to give a survey of current advances, outstanding challenges, and practical considerations in testing such hard, brittle, and anisotropic crystals.While the origin of mechanical strength, toughness, and creep resistance is well studied in most metals, much less is known about the properties of more complex crystal structuresdespite their wide use as reinforcement phases and the undiscovered potential in their sheer number and variability. A major challenge in plasticity research of the next years will therefore be to close this gap in knowledge. Small-scale testing techniques have been demonstrated as a key enabling technique for such studies. Most prominent is microcompression, which helps overcome the fundamental challenge of studying plasticity in materials, which suffer from extreme brittleness in conventional testing. [1,2] Their plastic properties may, at first glance, appear to be of only academic interest: aiming to deduce fundamental relationships of crystal plasticity and structure to enable knowledge-guided search and data mining for new structural materials. However, they are in fact essential to performance at the microstructural scale of many advanced and highly alloyed materials and to understanding the effects of alloying strategies aimed at inducing deformability as baseline or reference information. Investigating plasticity in hard crystalsA deep understanding of plasticity and dislocation motion exists in most metallic crystals and strategies to engineer different aspects, for example by adjustment of the stacking fault energy, have been very successful. [3,4] These are being applied-with great effect-to hexagonal metals [3] which in spite of their closely related atomic packing show strongly anisotropic deformation and are therefore much more difficult to deform at low temperatures. In BCC metals, fundamental aspects of dislocation core structure, stress tensor dependence, and resulting non-Schmid behavior, are also still under investigation. [5,6] However, in all of these materials, the availability of large-grained or single crystals with sufficient purity has scarcely been a problem, nor has the ability to deform such samples under carefully controlled conditions. Suitable investigations by conventional, analytical and high-resolution microscopy techniques have also been carried out whenever new methods have allowed researchers to dive deeper into the physics of their plastic deformation.In intermetallics, ceramics, and compounds we face challeng...

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“…Following these initial tests initiated on MgO, there was a wider effort to characterize the ionic rock salt crystals with LiF in the focus [133,215,217] using the same approach and including variable temperatures [206,218,219] and rates [220,221] with a combination with simulation [133]. An excerpt from these works is shown in Figure 26, highlighting the characteristics of the micro-compression tests described above for MgO: an increase in flow stress with size, which becomes more pronounced as the temperature is increased and, hence, the lattice resistance reduced [113,133].…”

Section: Rate and Temperature Dependence In Other Ionic Rock Salt Crymentioning

confidence: 99%

Dislocations and Plastic Deformation in MgO Crystals: A Review

et al. 2018

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This review paper focuses on dislocations and plastic deformation in magnesium oxide crystals. MgO is an archetype ionic ceramic with refractory properties which is of interest in several fields of applications such as ceramic materials fabrication, nano-scale engineering and Earth sciences. In its bulk single crystal shape, MgO can deform up to few percent plastic strain due to dislocation plasticity processes that strongly depend on external parameters such as pressure, temperature, strain rate, or crystal size. This review describes how a combined approach of macro-mechanical tests, multi-scale modeling, nano-mechanical tests, and high pressure experiments and simulations have progressively helped to improve our understanding of MgO mechanical behavior and elementary dislocation-based processes under stress.

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On extracting mechanical properties from nanoindentation at temperatures up to 1000 °C

Cited by 49 publications

References 60 publications

Mechanical characterisation of the protective Al2O3 scale in Cr2AlC MAX phases

Mechanical characterisation of the protective Al2O3 scale in Cr2AlC MAX phases

Microcompression of brittle and anisotropic crystals: recent advances and current challenges in studying plasticity in hard materials

Dislocations and Plastic Deformation in MgO Crystals: A Review

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