Effect of Grain Size Distribution on Tensile Properties of Electrodeposited Nanocrystalline Nickel

2000 ◽  
Vol 634 ◽  
Author(s):  
Fereshteh Ebrahimi ◽  
Zunayed Ahmed ◽  
Kristin L. Morgan
Keyword(s):  
Grain Size ◽  
Strain Hardening ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Tensile Elongation ◽  
Dislocation Motion ◽  
Nanocrystalline Nickel ◽  
Strain Behavior ◽  
Average Grain Size ◽  
Strain Hardening Rate

ABSTRACTWe have produced dense and ductile nanocrystalline nickel with various grain size distributions using electrodeposition techniques. The strength of the nickel deposits fell within the scatter band of the general Hall-Petch curve for nickel. However, large variations in yield strength, strain hardening rate and tensile elongation were associated with a relatively small change in the average grain size. The scatter in the elongation data has been attributed to the formation of nodules and the presence of voids. The variations in strength and strain hardening rate have been shown to be associated with the changes in the grain size distribution. A model based on confined dislocation motion and composite behavior has been developed for predicting the stress-strain behavior of the nanocrystalline nickel.

Recrystallization of Oxygen Contaminated Al Films

1986 ◽  
Vol 71 ◽  
Author(s):  
G.J. Van Der Kolk ◽  
M.J. Verkerk
Keyword(s):  
Grain Size ◽  
Silicon Nitride ◽  
Substrate Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Relative Increase ◽  
Partial Pressures ◽  
Average Grain Size

AbstractAl was evaporated at oxygen partial pressures, PO2, varying between 10−7 and 10−4 Pa on substrates of silicon nitride. The substrate temperature was varied between 20 °C and 250°C. The films were annealed at temperatures up to 500°C.For Al films deposited at 20°C, it was found that the average grain size decreases with increasing oxygen partial pressure. After annealing recrystallization was observed. The relative increase of grain size was less for higher values of pO2. Annealing gave rise to a broad grain size distribution.For Al films deposited at 250°C, the presence of oxygen caused the growth of rough inhomogeneous films. This inhomogeneous structure remained during annealing.

The Inverse Hall-Petch Effect—Fact or Artifact?

2000 ◽  
Vol 634 ◽  
Author(s):  
Carl C. Koch ◽  
J. Narayan
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Computer Simulations ◽  
Nanocrystalline Materials ◽  
Grain Sizes ◽  
Average Grain Size

ABSTRACTThis paper critically reviews the data in the literature which gives softening—the inverse Hall-Petch effect—at the finest nanoscale grain sizes. The difficulties with obtaining artifactfree samples of nanocrystalline materials will be discussed along with the problems of measurement of the average grain size distribution. Computer simulations which predict the inverse Hall-Petch effect are also noted as well as the models which have been proposed for the effect. It is concluded that while only a few of the experiments which have reported the inverse Hall-Petch effect are free from obvious or possible artifacts, these few along with the predictions of computer simulations suggest it is real. However, it seems that it should only be observed for grain sizes less than about 10 nm.

Variable Elastic-Plastic Properties of the Grain Boundaries and Their Effect on the Macroscopic Flow Stress of Nano-Crystalline Metals

2009 ◽  
Vol 1224 ◽  
Author(s):  
Malgorzata Lewandowska ◽  
Romuald Dobosz ◽  
Krzysztof J Kurzydlowski
Keyword(s):  
Grain Size ◽  
Flow Stress ◽  
Grain Boundaries ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Distribution Functions ◽  
Boundary Misorientation ◽  
Plastic Properties ◽  
Nano Crystalline ◽  
Average Grain Size

AbstractThe paper reports new experimental results describing properties and microstructure of nanocrystalline metals. Nano- and sub-micron aluminium has been produced by hydrostatic extrusion at ambient tempearture. The structures have been quantified in terms of size of grains and misorientation of the grain boundaries. Different average size of grains, variable normalized width of grain size distribution and changing grain boundary misorientation distribution functions have been revealed depending on processing parameters. The results of the tensile tests showed that the average grain size, grain size distribution and the distribution function of misorientation angles influence the flow stress of obtained nano-metals. In order to explain the observed difference in the properties of nano- and micro-sized aluminium alloys, a Finite Element Method models have been developed, which assumes that both grain boundaries and grain interiors may accommodated elastic and non-linear plastic deformation. These models assumed true geometry of grains (which differed in size and shape). Also, variable mechanical properties of grain boundaries have been taken into account (elastic modulus, yield strength and work hardening rate). The results of modelling explain in a semi-quantitative way macroscopic deformation of nano-crystalline aggregates. In particular, they illustrate the importance of the interplay between properties of grain boundaries and grain interiors in elastic and plastic regime.

Statistical analysis of the parameters and grain size distribution functions of single-phase polycrystalline materials

2020 ◽  
Vol 86 (4) ◽  
pp. 39-45
Author(s):  
S. I. Arkhangelskiy ◽  
D. M. Levin
Keyword(s):  
Grain Size ◽  
Distribution Function ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Single Phase ◽  
Distribution Functions ◽  
Grain Structure ◽  
Polycrystalline Materials ◽  
Grain Sizes ◽  
Average Grain Size

A statistical analysis of the grain size distribution is important both for developing theories of the grain growth and microstructure formation, and for describing the size dependences of various characteristics of the physical and mechanical properties of polycrystalline materials. The grain size distribution is also an important characteristic of the structure uniformity and, therefore, stability of the properties of the products during operation. Statistical Monte Carlo modeling of single-phase and equiaxed polycrystalline microstructures was carried out to determine the type of statistically valid distribution function and reliable estimates of the average grain size. Statistical parameters (mean values, variances, variation coefficient) and distribution functions of the characteristics of the grain microstructure were obtained. It is shown that the distribution function of the effective grain sizes for the studied polycrystal model is most adequately described by γ-distribution, which is recommended to be used in analysis of the experimental distribution functions of grain sizes of single-phase polycrystalline materials with equiaxed grains. The general average (mathematical expectation) of the effective grain size (projection diameter) with γ-distribution function (parameters of the distribution function are to be previously determined in analysis of the grain structure of polycrystalline materials) should be taken as a statistically valid and reliable estimate of the average grain size. The results of statistical modeling are proved by the experimental data of metallographic study of the microstructures of single-phase model and industrial materials with different degree of the grain structure heterogeneity.

The Effect of Grain Size Distribution on the Mechanical Properties of Nanometals

2008 ◽  
Vol 140 ◽  
pp. 185-190 ◽  
Author(s):  
T.B. Tengen ◽  
Tomasz Wejrzanowski ◽  
R. Iwankiewicz ◽  
Krzysztof Jan Kurzydlowski
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Flow Stress ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Deformation Mechanisms ◽  
Average Grain Size ◽  
Significant Interest ◽  
Size Dispersion ◽  
The Relationship

Predicting the properties of a material from knowledge of the internal microstructures is attracting significant interest in the fields of materials design and engineering. The most commonly used expression, known as Hall-Petch Relationship (HPR), reports on the relationship between the flow stress and the average grain size. However, there is much evidence that other statistical information that the grain size distribution in materials may have significant impact on the mechanical properties. These could even be more pronounced in the case of grains of the nanometer size, where the HPR is no longer valid and the Reverse-HPR is more applicable. This paper proposes a statistical model for the relationship between flow stress and grain size distribution. The model considered different deformation mechanisms and was used to predict mechanical properties of aluminium and copper. The results obtained with the model shows that the dispersion of grain size distribution plays an important role in the design of desirable mechanical properties. In particular, it was found that that the dependence of a material’s mechanical properties on grain size dispersion also follows the HPR to Inverse-HPR type of behaviour. The results also show that copper is more sensitive to changes in grain size distribution than aluminium.

The Issue of Grain Size Distribution Using Mean Field Models for Dynamic and Post-Dynamic Recrystallization

2016 ◽  
Vol 879 ◽  
pp. 1794-1799 ◽  
Author(s):  
Guillaume Smagghe ◽  
David Piot ◽  
Frank Montheillet ◽  
G. Perrin ◽  
A. Montouchet ◽  
...  
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Mean Field ◽  
304L Stainless Steel ◽  
Mean Field Model ◽  
Average Grain Size ◽  
Fundamental Equations ◽  
Good Agreement

A mean field model for discontinuous dynamic recrystallization (DDRX) has been developed and chained with a post-dynamic recrystallization (PDRX) model to predict transient and steady-state flow stresses and average grain sizes. Numerical results are compared with experimental data obtained on a 304L stainless steel yielding to a good agreement in terms of average grain size. However an unrealistic grain-size distribution is observed using DDRX, which affects results of the PDRX model. This result is discussed with respect to the fundamental equations of DDRX.

scholarly journals The effect of debris-flow sediment grain size distribution on fan forming processes

2021 ◽  
Author(s):  
Haruka Tsunetaka ◽  
Norifumi Hotta ◽  
Yuichi Sakai ◽  
Thad Wasklewicz
Keyword(s):  
Grain Size ◽  
Debris Flow ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Flow Characteristics ◽  
Granular Flows ◽  
Spatial Diversity ◽  
Flume Experiments ◽  
Sediment Grain Size ◽  
Average Grain Size

Abstract. Knowledge of the processes driving debris-flow fan evolution are critical in the support of efforts to mitigate related hazards, reduce risk to populations and infrastructure, and reconstruct the history of sediment dynamics in mountainous areas. Research on debris-flow fan development has focused on topographic controls, debris-flow volume and rheology, and the sequence of occurrence of debris flows. While these items have explained a great deal about fan formation and specifically avulsion and runout mechanisms, there is a need to further investigate other properties as they relate to debris-flow fan formative process. Here, we examined the role of debris-flow grain-size distribution on fan formation. Flume experiments were employed to examine the morphology of debris-flow fans that resulted from flows with mono- or multi-granular sediment composition with the same average grain size. All other flow characteristics were held constant. The mono-granular flows formed a symmetric-like fan morphology because there was little avulsion during the formation process. The multi-granular flows produced fans with an asymmetric morphology. Avulsions occurred on both lateral extents of the fan during the early stages of fan development and caused the runout direction to shift produce the fan asymmetry. Grain-size distribution was closely related to spatial diversity in fan morphology and stratigraphy.

scholarly journals Grain-size distribution analysis of Quaternary sediments from the southern part of the Lodz region in Poland: a computational-methods approach

Geologos ◽  
2011 ◽  
Vol 17 (4) ◽  
pp. 205-219 ◽  
Author(s):  
Lucyna Wachecka-Kotkowska ◽  
Paweł Kotkowski
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Computational Methods ◽  
Method Of Moments ◽  
Linear Interpolation ◽  
Unconsolidated Sediments ◽  
Distribution Analysis ◽  
Quaternary Sediments ◽  
Average Grain Size

Grain-size distribution analysis of Quaternary sediments from the southern part of the Lodz region in Poland: a computational-methods approachEighteen samples of Quaternary unconsolidated sediments from the Piotrków Plateau and the Radomsko Hills in central Poland have been analysed for their average grain size, sorting, skewness and kurtosis. The analysis was carried out by seven computational methods of interpolation and nine extrapolation methods. It appears that linear interpolation, the traditional method (DOS), and the Josek and Gradistat Programs give comparable results, but that quadratic interpolation and the method of moments should not be applied since they yield unreliable results. The method of moments gives unduly high or unduly low parameter values because of the application of different, i.e. incomparable measures in the applied formulae. It should be stressed that only extrapolation provides, if performed under the right conditions, the possibility to determine some parameters, in particular skewness values.

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