Accurate prediction of threshold stress for hydride reorientation in Zircaloy-4 with directly measured interface orientation relationship

Low dimensional nanostructures, e.g. nanowires, self-assembled through heteroepitaxy, present a variety of crystallographic features that do not always follow conventional V-W or S-K growth mode. Applying Δg parallelism rules and edge-to-edge matching (E2EM) model in β-DySi2/Si and CoSi2/Si systems provides a better understanding of the natural preference of the interface orientation and the orientation relationship (OR) during heteroepitaxial growth. This may help improving the quality of nanowires through optimizing the substrate orientation.

Download Full-text

The coprecipitation of Cr3P and Cr in Cu

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100105886 ◽

1988 ◽

Vol 46 ◽

pp. 764-765

Author(s):

M.J. Witcomb ◽

U. Dahmen ◽

K.H. Westmacott

Keyword(s):

Orientation Relationship ◽

Interface Structure ◽

Model System ◽

Relative Orientation ◽

Age Hardening ◽

Precipitation Behavior ◽

Solution Treated ◽

Small Needle ◽

Diffraction Patterns ◽

Interface Structures

Cu-Cr age-hardening alloys are of interest as a model system for the investigation of fcc/bcc interface structures. Several past studies have investigated the morphology and interface structure of Cr precipitates in a Cu matrix (1-3) and good success has been achieved in understanding the crystallography and strain contrast of small needle-shaped precipitates. The present study investigates the effect of small amounts of phosphorous on the precipitation behavior of Cu-Cr alloys.The same Cu-0.3% Cr alloy as was used in earlier work was rolled to a thickness of 150 μm, solution treated in vacuum at 1050°C for 1h followed by quenching and annealing for various times at 820 and 863°C.Two laths and their corresponding diffraction patterns in an alloy aged 2h at 820°C are shown in correct relative orientation in Fig. 1. To within the limit of accuracy of the diffraction patterns the orientation relationship was that of Kurdjumov-Sachs (KS), i.e. parallel close-packed planes and directions.

Download Full-text

The effects of strain and strain rate on residual microstructures in copper

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143687 ◽

1986 ◽

Vol 44 ◽

pp. 420-421

Author(s):

M. F. Stevens ◽

P. S. Follansbee

Keyword(s):

Strain Rate ◽

Applied Stress ◽

Threshold Stress ◽

Rate Sensitivity ◽

Viscous Drag ◽

Strain Rates ◽

Strain And Strain Rate ◽

Threshold Strength ◽

Mechanism Transition ◽

Intrinsic Strength

The strain rate sensitivity of a variety of materials is known to increase rapidly at strain rates exceeding ∼103 sec-1. This transition has most often in the past been attributed to a transition from thermally activated guide to viscous drag control. An important condition for imposition of dislocation drag effects is that the applied stress, σ, must be on the order of or greater than the threshold stress, which is the flow stress at OK. From Fig. 1, it can be seen for OFE Cu that the ratio of the applied stress to threshold stress remains constant even at strain rates as high as 104 sec-1 suggesting that there is not a mechanism transition but that the intrinsic strength is increasing, since the threshold strength is a mechanical measure of intrinsic strength. These measurements were made at constant strain levels of 0.2, wnich is not a guarantee of constant microstructure. The increase in threshold stress at higher strain rates is a strong indication that the microstructural evolution is a function of strain rate and that the dependence becomes stronger at high strain rates.

Download Full-text

Adolescent Cultural and Racial Orientation: Relationship to Political Identity

PsycEXTRA Dataset ◽

10.1037/e628622012-331 ◽

2005 ◽

Author(s):

O. Cartman

Keyword(s):

Orientation Relationship ◽

Political Identity

Download Full-text

Accurate Prediction of Fatigue Life under Random Loading

Journal of the Society of Materials Science Japan ◽

10.2472/jsms.61.853 ◽

2012 ◽

Vol 61 (10) ◽

pp. 853-859 ◽

Cited By ~ 5

Author(s):

Norio TAKEDA ◽

Tomohiro NARUSE

Keyword(s):

Fatigue Life ◽

Accurate Prediction ◽

Random Loading

Download Full-text

Combining First-Principles and Data Modeling for the Accurate Prediction of the Refractive Index of Organic Polymers

10.26434/chemrxiv.5446564 ◽

2017 ◽

Author(s):

Mohammad Atif Faiz Afzal ◽

Chong Cheng ◽

Johannes Hachmann

Keyword(s):

First Principles ◽

Data Modeling ◽

Accurate Prediction ◽

Index Of Refraction ◽

Structure Theory ◽

Organic Polymers ◽

Number Density ◽

Lorenz Equation ◽

In Silico Studies ◽

Wide Range

Organic materials with a high index of refraction (RI) are attracting considerable interest due to their potential application in optic and optoelectronic devices. However, most of these applications require an RI value of 1.7 or larger, while typical carbon-based polymers only exhibit values in the range of 1.3–1.5. This paper introduces an efficient computational protocol for the accurate prediction of RI values in polymers to facilitate in silico studies that an guide the discovery and design of next-generation high-RI materials. Our protocol is based on the Lorentz-Lorenz equation and is parametrized by the polarizability and number density values of a given candidate compound. In the proposed scheme, we compute the former using first-principles electronic structure theory and the latter using an approximation based on van der Waals volumes. The critical parameter in the number density approximation is the packing fraction of the bulk polymer, for which we have devised a machine learning model. We demonstrate the performance of the proposed RI protocol by testing its predictions against the experimentally known RI values of 112 optical polymers. Our approach to combine first-principles and data modeling emerges as both a successful and highly economical path to determining the RI values for a wide range of organic polymers.

Download Full-text