Activation energy for plastic flow in nanocrystalline CoCrFeMnNi high-entropy alloy: A high temperature nanoindentation study

Lee, Dong Hoon; Choi, In Chul; Yang, Guixia; Liu, Xiongjun; Kawasaki, Megumi; Ramamurty, Upadrasta; Schwaiger, Ruth; Jang, Jae-il

doi:10.1016/j.scriptamat.2018.07.014

Cited by 51 publications

(23 citation statements)

References 38 publications

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“…Uniformly distributed nano-grains, shown by the bright-field TEM image, and the diffraction rings shown by the SAED pattern together reveal that extreme grain refinement has been achieved at the surface of the RASP-MEA sample. Statistical analysis based on a series of TEM images produced the grain size distribution chart shown in Figure 3 c. The average grain size at the surface is estimated to be 37 nm, which is towards the lower bond of the nano-crystalline regime [ 46 , 47 , 48 ]. In contrast, the grain refinement at the surface layer of RASP-Ni is not as significant as in RASP-MEA.…”

Section: Resultsmentioning

confidence: 99%

Effective Surface Nano-Crystallization of Ni2FeCoMo0.5V0.2 Medium Entropy Alloy by Rotationally Accelerated Shot Peening (RASP)

Liang

Wang

Cao

et al. 2020

Entropy

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The surface nano-crystallization of Ni2FeCoMo0.5V0.2 medium-entropy alloy was realized by rotationally accelerated shot peening (RASP). The average grain size at the surface layer is ~37 nm, and the nano-grained layer is as thin as ~20 μm. Transmission electron microscopy analysis revealed that deformation twinning and dislocation activities are responsible for the effective grain refinement of the high-entropy alloy. In order to reveal the effectiveness of surface nano-crystallization on the Ni2FeCoMo0.5V0.2 medium-entropy alloy, a common model material, Ni, is used as a reference. Under the same shot peening condition, the surface layer of Ni could only be refined to an average grain size of ~234 nm. An ultrafine grained surface layer is less effective in absorbing strain energy than a nano-grain layer. Thus, grain refinement could be realized at a depth up to 70 μm in the Ni sample.

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Section: Resultsmentioning

confidence: 99%

Effective Surface Nano-Crystallization of Ni2FeCoMo0.5V0.2 Medium Entropy Alloy by Rotationally Accelerated Shot Peening (RASP)

Liang

Wang

Cao

et al. 2020

Entropy

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“…Для поликристаллического Ni она составила U a = 216 kJ/mol при ε = 0.002 s −1 [154], что также согласуется с данными других авторов, полученных в макроиспытаниях. В [81] схожим образом с помощью высокотемпературного NI были определены активационная энергия U a и активационный объем V a в высокоэнтропийном нанокристаллическом сплаве CoCrFeMnNi. Отмечается, что величина U a растет от ∼ 0.5 до ∼ 1.8 eV при увеличении T от 473 до 523 K (что соответствует ∼ 0.3 и ∼ 0.34 от температуры плавления T m ), а коэффициент скоростной чувствительности m = ∂(ln H/∂ lnε) увеличивается с ∼ 0.015 до ∼ 0.1.…”

Section: высокотемпературное наноиндентированиеunclassified

Наноиндентирование И Механические Свойства Материалов В Субмикро- И Наношкале. Недавние Результаты И Достижения (О Б З О Р)

Головин¹

2021

Физика Твердого Тела

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The review discusses the details of various materials mechanical behavior in submicro- and nanoscale. Significant advances in this scope result from the development of wide family of load based precise nanotesting techniques called nanoindentation. But nowadays, nanomechanical properties are studied not only by nanoindentation techniques in narrow sense, i.e. local loading of macro, micro and nanoscale objects. Nanomechanical load testing is discussed here within a wider scope employing precise deformation measurement with nanometer scale resolution caused by various types of low load application to the object under study including uniaxial compression or extension, shearing, bending or twisting, optionally accompanied by in situ monitoring sample microstructure using scanning and transmission electron microscopy and Laue microdiffraction technique. The main courses of experimental techniques development in recent ten years along with the results obtained using them in single, poly and nano crystalline materials, composites, films and coatings, amorphous solids and such biomaterials as tissues, living cells and macromolecules are described. Special attention is paid to deformation size effects and atomic mechanisms in nanoscale. This review is a natural continuation and development of the review published at Fiz.Tverd.Tela vol.50, issue 12, 2008 of the same author that discusses details of nanomechanical properties of solids. Current review includes wider range of nanomechanical testing concepts and recent achievements in the scope. The work was supported by RFBR grant for project #19-12-50235.

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“…Therefore, the standard approaches used in mass samples are not ideal for thin films [ 4 ]. Environmental conditions of the films such as temperature and moisture can have a direct influence on their mechanical properties [ 4 , 5 , 6 ]. Few methods exist to measure the surface strength of thin films, which in recent years have gained greater attention from the nanoindentation experiment.…”

Section: Introductionmentioning

confidence: 99%

A Molecular Dynamics Investigation of the Temperature Effect on the Mechanical Properties of Selected Thin Films for Hydrogen Separation

Oyinbo

Jen

2020

Membranes

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In this study, we performed nanoindentation test using the molecular dynamic (MD) approach on a selected thin film of palladium, vanadium, copper and niobium coated on the vanadium substrate at a loading rate of 0.5 Å/ps. The thermosetting control is applied with temperature variance from 300 to 700 K to study the mechanical characteristics of the selected thin films. The effects of temperature on the structure of the material, piling-up phenomena and sinking-in occurrence were considered. The simulation results of the analysis and the experimental results published in this literature were well correlated. The analysis of temperature demonstrated an understanding of the impact of the behaviour. As the temperature decreases, the indentation load increases for loading and unloading processes. Hence, this increases the strength of the material. In addition, the results demonstrate that the modulus of elasticity and thin-film hardness decreases in the order of niobium, vanadium, copper and palladium as the temperature increases.

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Activation energy for plastic flow in nanocrystalline CoCrFeMnNi high-entropy alloy: A high temperature nanoindentation study

Cited by 51 publications

References 38 publications

Effective Surface Nano-Crystallization of Ni2FeCoMo0.5V0.2 Medium Entropy Alloy by Rotationally Accelerated Shot Peening (RASP)

Effective Surface Nano-Crystallization of Ni2FeCoMo0.5V0.2 Medium Entropy Alloy by Rotationally Accelerated Shot Peening (RASP)

Наноиндентирование И Механические Свойства Материалов В Субмикро- И Наношкале. Недавние Результаты И Достижения (О Б З О Р)

A Molecular Dynamics Investigation of the Temperature Effect on the Mechanical Properties of Selected Thin Films for Hydrogen Separation

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