Sample Dimensions Influence Strength and Crystal Plasticity

Uchic, Michael D.; Dimiduk, Dennis M.; Florando, J.N.; Nix, William D.

doi:10.1126/science.1098993

Cited by 2,059 publications

(1,165 citation statements)

References 17 publications

Supporting

Mentioning

1,086

Contrasting

Unclassified

Order By: Relevance

“…These results are quite different from the results obtained from a series of small-scale experiments on face-centered cubic (fcc) single crystals of arguably lower crystal quality, which demonstrate smaller strengths with less scatter, and a clear size effect ("smaller is stronger"). [28][29][30][31][32][33] This behavior has been attributed to constrained dislocation interactions and geometrical limitations of source size for samples with dimensions between around 200 nm and 10 µm. For smaller samples, it is observed that dislocations run out of the samples, 34,35 leaving dislocation nucleation the only possible process for controlling further deformation.…”

mentioning

confidence: 99%

Ultrahigh Strength Single Crystalline Nanowhiskers Grown by Physical Vapor Deposition

et al. 2009

View full text Add to dashboard Cite

The strength of metal crystals is reduced below the theoretical value by the presence of dislocations or by flaws that allow easy nucleation of dislocations. A straightforward method to minimize the number of defects and flaws and to presumably increase its strength is to increase the crystal quality or to reduce the crystal size. Here, we describe the successful fabrication of high aspect ratio nanowhiskers from a variety of face-centered cubic metals using a high temperature molecular beam epitaxy method. The presence of atomically smooth, faceted surfaces and absence of dislocations is confirmed using transmission electron microscopy investigations. Tensile tests performed in situ in a focusedion beam scanning electron microscope on Cu nanowhiskers reveal strengths close to the theoretical upper limit and confirm that the properties of nanomaterials can be engineered by controlling defect and flaw densities.Single crystalline metal wires, or metal whiskers, with diameters larger than one micrometer have been routinely fabricated 1 and used for experimentally examining mechanical, 2 ferromagnetic, 3 superconductive, 4 and electronic 5 properties. Interest in metal whiskers became intense once it was observed that they could exhibit strengths close to theoretical (ideal) values. 2,6 Whiskers have been grown by the vapor liquid solid method 7 (VLS) or metal halide reduction, 6 the latter of which have demonstrated high strength. 6 This has been attributed to the near-equilibrium nature of the growth process and the resultant absence of defects and flaws in the samples. Extending the fabrication of high quality metal whiskers to submicrometer diameters, as routinely produced for semiconductors, 7-9 is clearly desired but has been largely elusive. However, single crystalline metal nanowires have only occasionally been successfully fabricated. 10 Here we describe the first time to our knowledge the fabrication of metal single crystalline nanowhiskers (NWs) with diameters as small as 20 nm and no defects, as evidenced by their strengths near the theoretical upper limit. Such nanostructures have the potential to serve as model systems for elucidating intrinsic properties in tiny structures, such as quantum effects, and to be used as building blocks in nanotechnological applications where unique functionalities are required.In this study, free-standing, high aspect ratio, single crystalline nanowhiskers of a variety of different materials (copper, gold, silver, aluminum, and silicon) have been successfully grown from partially C-coated, oxidized and nonoxidized Si (100), (110), and (111) substrates under molecular beam epitaxy (MBE) conditions. Both elevated substrate temperatures (on the order of 0.65 T M of the deposited species) and the partial C layer are necessary to achieve nanowhisker growth. In the remainder of this publication we will focus on results from Cu nanowhiskers. Figure 1 shows scanning electron micrographs of two Cu samples with nominal Cu thicknesses of 45 and 200 nm, respectively. In addi...

show abstract

mentioning

confidence: 99%

Ultrahigh Strength Single Crystalline Nanowhiskers Grown by Physical Vapor Deposition

et al. 2009

View full text Add to dashboard Cite

show abstract

“…T he deformation behaviour of small-volume metals, in particular the effects of sample size (that is, the diameter D of micro-and nano-pillars) on the apparent strength σ, has been attracting considerable attention recently [1][2][3][4][5][6][7] . A number of studies of single-crystal micro-and nano-pillars have demonstrated the 'smaller is stronger' trend, with the flow stress increasing markedly with decreasing sample size.…”

mentioning

confidence: 99%

A new regime for mechanical annealing and strong sample-size strengthening in body centred cubic molybdenum

Huang

Shan

et al. 2011

Nat Commun

View full text Add to dashboard Cite

Because of crystal symmetry, body centred cubic (BCC) metals have large differences in lattice friction between screw and edge dislocations, and manifest generally different mechanical behaviours from face centred cubic (FCC) metals. Although mechanical annealing (significant drop in stored dislocation density in response to applied stress) has been observed in FCC metals, it has not been observed in BCC metals so far. Here we show that significant mechanical annealing does occur in BCC mo pillars, when their diameters decrease to hundreds of nanometers. In addition, there exists a critical diameter for focused ion beam milled pillars, below which the strengthening exponent increases dramatically, from ~0.3 to ~1. Thus, a new regime of size effects in BCC metals is discovered that converges to that of FCC metals, revealing deep connection in the dislocation dynamics of the two systems.

show abstract

“…Также следует помнить, что пластичность ОМС зависит не только от абсолютного размера образ-ца, но и от геометрического соотношения ширины (или диаметра) к высоте [48,49], которое оказывает влияние на формирование полос сдвига и дефор-мационные процессы [50,51]. Образцы с соотно-шением высоты к диаметру ≤1 показывают высо-кую пластичность [27,52] образцов Zr-Ti-Ni-Cu-Be с надрезом при вве-дении усталостных трещин была значительно ни-же -18,4±1,4 МПа·√ -м [54].…”

Section: рис 2 схематическое изображение полос сдвигаunclassified

Properties of Bulk Metallic Glasses

Luzgin¹,

Polkin²

2016

Izv.VUZ. Tsvet. Met.

View full text Add to dashboard Cite

Металловедение и термическая обработка Izvestiya vuzov. Tsvetnaya metallurgiya • 6 • 2016 71 ВведениеМеталлические стекла, получаемые в виде тон-ких чешуек или лент, известны со второй полови-ны прошлого века [1]. Объемные металлические стекла (ОМС) с минимальным размером порядка 100-102 мм в каждом из 3 пространственных из-мерений [2] изначально были получены в системах Pd-Cu-Si и Pd-Ni-P, но ввиду исключительной дороговизны основного компонента (палладия) долгое время не представляли особого интере-са для ученых и инженеров. Впоследствии ОМС, полученные во многих других системах, включая технологически важные -на основе Fe, Mg, Ti и За последние несколько десятилетий открыто относительно небольшое число революционных материалов в области ме-талловедения и физики металлов, и объемные металлические стекла одни из них. Их прочность и твердость значительно выше, а модуль упругости ниже, чем кристаллических сплавов, что приводит к высокой энергии запасенной упругой деформации. Эти материалы также имеют очень хорошую устойчивость к коррозии. В настоящей работе исследованы свойства объемных металлических стекол, в частности тепловые, механические, магнитные, электрические показатели и коррозионная стойкость, а также приводятся области применения данных сплавов. Louzguine-Luzgin D.V., Pol'kin V.I. Properties of bulk metallic glassesA relatively small number of revolutionary discoveries were made in the field of metallurgy and metal physics in the last few decades, and bulk metallic glasses are one of them. The strength and hardness of bulk metallic glasses are much higher while moduli of elasticity are lower than those of crystalline alloys which results in high stored elastic strain energy. These alloys also have very good corrosion resistance. This article covers various properties of bulk metallic glasses, in particular thermal, mechanical, magnetic, electrical properties and corrosion resistance as well as applications of these alloys.Keywords: bulk metallic glasses, strength, ductility, application.

show abstract

Sample Dimensions Influence Strength and Crystal Plasticity

Cited by 2,059 publications

References 17 publications

Ultrahigh Strength Single Crystalline Nanowhiskers Grown by Physical Vapor Deposition

Ultrahigh Strength Single Crystalline Nanowhiskers Grown by Physical Vapor Deposition

A new regime for mechanical annealing and strong sample-size strengthening in body centred cubic molybdenum

Properties of Bulk Metallic Glasses

Contact Info

Product

Resources

About