Low temperature heat capacity and thermal stability of nanocrystalline nickel

Wang, Lan; Tan, Zhi‐Cheng; Sun, Meng; Liang, Dongbai; Liu, Beiping

doi:10.1016/s0040-6031(01)00724-9

Cited by 9 publications

(5 citation statements)

References 12 publications

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“…9͒ as well as with the increase in 3% measured in NC Ni. 10 The results presented here demonstrate that the structural disorder of the interfaces has a minor contribution to the anomalous behavior of the lattice specific heat of NC materials. Sample C, for example, characterized with X IC = 0.21, mean grain size 13.4͑5͒ nm and intercrystalline layer thickness of 1.0͑5͒ nm ͑typical value for the NC interface thickness regardless of the synthesizing method͒, reveals an increase in only 0.18% compared to the bulk value.…”

Section: B Thermodynamic and Elastic Propertiesmentioning

confidence: 57%

Vibrational thermodynamics ofFe90Zr7B3nanocrystalline alloy from nuclear inelastic scattering

et al. 2010

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Recently we determined the iron-partial density of vibrational states ͑DOS͒ of nanocrystalline Fe 90 Zr 7 B 3 ͑Nanoperm͒, synthesized by crystallization of an amorphous precursor, for various stages of nanocrystallization separating the DOS of the nanograins from that of the interfaces ͓S. Stankov, Y. Z. Yue, M. Miglierini, B. Sepiol, I. Sergueev, A. I. Chumakov, L. Hu, P. Svec, and R. Rüffer, Phys. Rev. Lett. 100, 235503 ͑2008͔͒. Here we present quantitative analysis of the evolution of various thermoelastic properties calculated from DOS such as mean-force constant, mean atomic displacement, vibrational entropy, and lattice specific heat as the material transforms from amorphous, through nanocrystalline, to fully crystallized state. The reported results shed new light on the previously observed anomalies in the vibrational thermodynamics of nanocrystalline materials.

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Section: B Thermodynamic and Elastic Propertiesmentioning

confidence: 57%

Vibrational thermodynamics ofFe90Zr7B3nanocrystalline alloy from nuclear inelastic scattering

et al. 2010

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“…A series of novel physical and chemical properties of the nanocrystals, such as high diffusivity and reactivity, great ductibility, large thermal expansion, enhanced phonon specific heat, and a significant change in the magnetic susceptibility, relative to the corresponding coarse-grained polycrystals, have captured the attention of the scientists and engineers because of their potential application [1]. We measured heat capacities of nanocrystalline nickel [35] and copper in the temperature range from 78 to 370 K, and studied the heat capacity enhancement relative to the corresponding coarse-grained metal crystal. The two samples were produced by Zhengyuan Nano-materials Engineering Corp. (Shandong, China).…”

Section: Nanocrystalline Metalsmentioning

confidence: 99%

Study of heat capacity enhancement in some nanostructured materials

Tan

Wang

Shi

2009

Pure and Applied Chemistry

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Heat capacity properties of some nanostructured oxides, metals, and zeolites were studied, mainly with the aid of low-temperature adiabatic calorimetry. Obvious enhancement in the heat capacity of nanostructured materials to different degrees was observed as compared with the corresponding coarse-grained materials. The contributions of enhanced heat capacity of nanostructured materials toward properties such as density, thermal expansion, sample purity, surface effect, and size effect are discussed.

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“…The surface morphology of the nano-Ni sample tested at 777 K showed the presence of oxide layer of ~1−5 µm thick. Wang et al [22] studied the oxidation behavior of nano-Ni with a grain size of ~40 nm using thermogravimetry and reported strong oxidation of nano-Ni at temperatures > 500 K. Chan et al [23] also reported static and dynamic oxidation of nano-Ni in tension at temperatures > 673 K. The fine grain size in nano-Ni can enhance the oxidation tendency even at low temperatures. These studies suggest that the oxide layer formation on nano-Ni tensile specimens is inevitable at test temperatures >673 K. The oxide layer formed on surface of the specimen can start influencing the properties when the ratio of specimen thickness to oxide layer and the t/d ratio decrease.…”

Section: Discussionmentioning

confidence: 99%

Specimen size effect on superplastic flow behavior of electrodeposited nanocrystalline nickel

Prasad¹

2015

LoM

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Nanocrystalline nickel foils with a grain size of ~12 nm are produced by pulsed current electrodeposition using a modified Watts electrolytic bath. Saccharin, a sulfur-based organic compound, used as a grain refiner and stress reliever to produce free-standing Ni foils. Nano-Ni tensile specimens displayed superplastic elongations (>400 %) at high strain rate of 3×10 -1 s -1 and relatively low temperature of 777 K. Tensile specimens with different gauge lengths and thicknesses exhibited significant specimen size effect on maximum stress, elongation to failure and flow behavior under superplastic conditions. An increased total elongation to failure with increasing the specimen thickness and decreasing the gauge length was observed in the electrodeposited Ni foils. The stress-strain behavior of Ni changed from strain hardening to strain softening with increasing the specimen thickness. Strain rate jump tests indicated a very high strain rate sensitivity index values (m~0.5-0.8) for nano-Ni specimens at 777 K with a slight increased value of m with increasing the specimen thickness. The as-deposited nano-Ni samples showed substantial grain growth during heating and deformation as well at the testing temperature of 777 K. Microstructural investigation revealed that the total number of grains across specimen thickness and the formation of oxide layer during high temperature deformation can influence the superplasticity characteristics of nanocrystalline Ni. Влияние размера образца на сверхпластическое поведение электроосажденного нанокристаллического никеляПутем электроосаждения пульсирующим током в модифицированной электролитической ванне Уоттса получены фольги нанокристаллического никеля с размером зерен около 12 нм. Для получения отделенных фольг никеля, измельчения зерен и релаксации напряжений было использовано органическое вещество на основе серы -сахарин. Образцы нано-никеля для растяжения продемонстрировали сверхпластические удлинения (выше 400%) при высокой скорости деформации 3×10 -1 c -1 и относительно низкой температуре 777 K. Образцы для растяжения с различными длинами рабочих частей и толщинами показали значительное влияние размера образцов на максимальное напряжение, удлинение до разрушения и характер течения в условиях сверхпластичности. На электроосажденных образцах Ni наблюдалось увеличение полного удлинения до разрушения с увеличением толщины образцов и уменьшением рабочей длины. Характер кривой напряжение-деформация Ni изменился от упрочнения к разупрочнению с увеличением толщины образцов. Испытания со скачком скорости деформации показали очень высокий показатель скоростной чувствительности (m~0.5-0.8) для образцов нано-Ni при 777 K с небольшим повышением значения m с увеличением толщины образцов. Образцы электроосажденного нано-Ni показали существенный рост зерен при нагреве и деформации, а также при температуре испытаний of 777 K. Микроструктурные исследования показали, что на характеристики сверхпластичности нанокристаллического Ni могут влиять полное число зерен по толщине образца и образование ...

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Low temperature heat capacity and thermal stability of nanocrystalline nickel

Cited by 9 publications

References 12 publications

Vibrational thermodynamics ofFe90Zr7B3nanocrystalline alloy from nuclear inelastic scattering

Vibrational thermodynamics ofFe90Zr7B3nanocrystalline alloy from nuclear inelastic scattering

Study of heat capacity enhancement in some nanostructured materials

Specimen size effect on superplastic flow behavior of electrodeposited nanocrystalline nickel

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