Instrumented nanoindentation investigation into the mechanical behavior of ceramics at moderately elevated temperatures

Bhakhri, Vineet; Wang, Qianqian; Ur-Rehman, Naeem; Ciurea, Constantin; Giuliani, Finn; Vandeperre, Luc

doi:10.1557/jmr.2011.246

Cited by 19 publications

(14 citation statements)

References 55 publications

(48 reference statements)

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“…A representative bulk yield stress then needs to be estimated from macroscopic data collected at high temperatures and extrapolated toward lower temperatures. This approach includes significant errors in the application of any type of equation describing thermal activation and the resulting Peierls barrier or lattice resistance at temperatures above 0 K, such as [65,66] …”

Section: Prospective Articlementioning

confidence: 99%

“…[65,67] There are several parameters, which are difficult to determine accurately in a small-scale experiment, even if the microsample has been machined from the same bulk material, as the dislocation density may have been changed by FIB milling [68] and be affected by dislocation exhaustion during deformation. [69] In addition, the shear strain rate may vary locally for a tapered pillar.…”

Section: Prospective Articlementioning

confidence: 99%

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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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Section: Prospective Articlementioning

confidence: 99%

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

View full text Add to dashboard Cite

show abstract

“…Bhakhri et al [41] discuss how this is possible using modern indenters, which record load and displacement during an indentation experiment so that the strain rate dependence of hardness can be determined. In deriving the strain rate for ceramic materials, again, the elastic nature of the indentation process needs to be accounted for as only the strain rate due to plastic deformation should be used.…”

Section: Lattice Resistance To Dislocation Glidementioning

confidence: 99%

“…An alternative approach to describing the resistance of other obstacles, taken by Ashby and Frost [62], is to use a single descriptive equation similar in nature to the one derived for glide controlled by the lattice resistance: Wang [63]. Experimental data taken from the following sources: hardness [41,44,73,74] and creep and flow stress measurements [65,75]. (10.14) where obstacle as before is the shear stress needed to overcome the obstacle resistance without thermal energy.…”

Section: Dislocation Glide Controlled By Other Obstaclesmentioning

confidence: 99%