scholarly journals Reproducible Orientation Relationships Developed from Phase Transformations—Role of Interfaces

Crystals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1042
Author(s):  
Wen-Zheng Zhang

The orientation relationship (OR) between phases related by a phase transformation is often reproducible. This study interprets and predicts the reproducible ORs with a two-stage approach. The initial OR formed at the nucleation stage tends to allow a periodic structure of a preferred state to form in the interface. A matching correspondence of either a one-to-one or n-to-m nature can be specified in the periodic structure. An initial OR will become the final reproducible OR if there is no misfit. Otherwise, a reproducible OR developed at the growth stage tends to permit a singular dislocation structure to form in an interface where the preferred state must be sustained locally. The actual change in the OR is subject to the given material system and the phase-transformation condition. Various singular dislocation structures and their constraints on the ORs are analyzed, with thermodynamics and kinetics applied conceptually. The resulting ORs can be specified by following one or more Δg parallelism rules. A set of workable steps is provided to facilitate the interpretation of observed reproducible ORs. Some unsolved problems are identified, which call for further studies that can quantitatively combine the thermodynamics, kinetics and crystallography of phase transformations.

2010 ◽  
Vol 58 (2) ◽  
pp. 255-265 ◽  
Author(s):  
H. Bhadeshia

Phase transformations contributing to the properties of modern steelsThe role of phase transformation theory in contributing to the development of innovative steels is assessed, focusing on examples where the relationship is transparent. Virtually all of the major transformations, ranging from those which necessarily involve diffusion, to others where the change in crystal structure is achieved by a deformation, are considered.


2018 ◽  
Author(s):  
Nicola Molinari ◽  
Jonathan P. Mailoa ◽  
Boris Kozinsky

<div> <div> <div> <p>The model and analysis methods developed in this work are generally applicable to any polymer electrolyte/cation-anion combination, but we focus on the currently most prominent polymer electrolyte material system: poly(ethylene) oxide/Li- bis(trifluoromethane) sulfonamide (PEO + LiTFSI). The obtained results are surprising and challenge the conventional understanding of ionic transport in polymer electrolytes: the investigation of a technologically relevant salt concentration range (1 - 4 M) revealed the central role of the anion in coordinating and hindering Li ion movement. Our results provide insights into correlated ion dynamics, at the same time enabling rational design of better PEO-based electrolytes. In particular, we report the following novel observations. 1. Strong binding of the Li cation with the polymer competes with significant correlation of the cation with the salt anion. 2. The appearance of cation-anion clusters, especially at high concentration. 3. The asymmetry in the composition (and therefore charge) of such clusters; specifically, we find the tendency for clusters to have a higher number of anions than cations.</p> </div> </div> </div>


2018 ◽  
Author(s):  
Nicola Molinari ◽  
Jonathan P. Mailoa ◽  
Boris Kozinsky

<div> <div> <div> <p>The model and analysis methods developed in this work are generally applicable to any polymer electrolyte/cation-anion combination, but we focus on the currently most prominent polymer electrolyte material system: poly(ethylene) oxide/Li- bis(trifluoromethane) sulfonamide (PEO + LiTFSI). The obtained results are surprising and challenge the conventional understanding of ionic transport in polymer electrolytes: the investigation of a technologically relevant salt concentration range (1 - 4 M) revealed the central role of the anion in coordinating and hindering Li ion movement. Our results provide insights into correlated ion dynamics, at the same time enabling rational design of better PEO-based electrolytes. In particular, we report the following novel observations. 1. Strong binding of the Li cation with the polymer competes with significant correlation of the cation with the salt anion. 2. The appearance of cation-anion clusters, especially at high concentration. 3. The asymmetry in the composition (and therefore charge) of such clusters; specifically, we find the tendency for clusters to have a higher number of anions than cations.</p> </div> </div> </div>


Author(s):  
Ирина Викторовна Евстафьева

В статье исследуются вопросы попечительства в отношении несовершеннолетних, отбывающих наказание в виде лишения свободы. Проблема, поднимаемая автором настоящей статьи, многогранна, касается различных аспектов отбывания наказания несовершеннолетними в воспитательных колониях и требует комплексного исследования, способного ответить на определенно значимый вопрос: является ли колония законным представителем находящихся в ней несовершеннолетних со всеми вытекающими из статуса законных представителей последствиями. При этом необходимо обращать внимание на специфику правового статуса лиц, отбывающих наказание в воспитательных колониях, которые, во-первых, являются несовершеннолетними, то есть не обладают дееспособностью в полном объеме и нуждаются в особой заботе, защите и представительстве, а во-вторых, осуждены за совершение тяжкого или особо тяжкого преступления, влекущего изоляцию от общества и определенные ограничения и лишения. Отечественное законодательство достаточно детально регламентирует особенности режима отбывания наказания в виде лишения свободы несовершеннолетними, не определяя при этом статуса воспитательных колоний, кем они являются: воспитателями, попечителями или исключительно учреждениями исполнения наказаний. Между тем правильное понимание значения и роли воспитательной колонии в жизни находящихся в ней несовершеннолетних преступников, по мнению автора, поможет избежать ряда проблем, объективно складывающихся в учреждениях подобного рода. С этой точки зрения предлагаемая тема представляет интерес не только для ученых-теоретиков, но и для практиков - сотрудников соответствующих учреждений. Особо следует подчеркнуть, что исследований по данной тематике в специальной литературе нет. Отдельные исследования, встречающиеся в современной литературе, касаются исключительно общего гражданско-правового статуса несовершеннолетних осужденных. Однако это обстоятельство может свидетельствовать только о новизне данной темы, но никак не об отсутствии самой проблемы. The article analyzes the issues of the status of educational colonies as guardians of minors serving a sentence of imprisonment. In fact, the problem raised by the author of this article is multifaceted, concerns various aspects of the serving of punishment by minors in educational colonies and requires a comprehensive study that can answer, it seems, a definitely significant question: whether the colony is the legal representative of the minors in it with all the consequences arising from the status of legal representatives in the form of duties and responsibilities. At the same time, it seems, it is necessary to pay attention to the specifics of the legal status of citizens serving sentences in educational colonies, who, firstly, are minors, i.e. do not have full legal capacity and need special care, protection and representation, and, secondly, are convicted of committing a serious or particularly serious crime, entailing isolation from society and certain restrictions and deprivation. Domestic legislation regulates in sufficient detail the peculiarities of the regime of serving sentences in the form of deprivation of liberty by minors, without determining the status of educational colonies. Who are they: educators, Trustees or only institutions of execution of punishments. Meanwhile, the correct understanding of the importance and role of the educational colony in the life of juvenile offenders in it, according to the author, will help to avoid a number of problems that objectively develop in institutions of this kind. From this point of view, the proposed topic is of interest not only for theoretical scientists, but for practitioners-employees of relevant institutions. It should be emphasized that there are no studies on this subject in the special literature. However, this circumstance can testify only about novelty of the given subject, but in any way about absence of the problem. It seems that the relevance and importance of a problem is not always measured by the number of studies devoted to it. Sometimes these its traits are manifest only under particularly careful consideration.


1988 ◽  
Vol 53 (12) ◽  
pp. 3072-3079
Author(s):  
Mojmír Skokánek ◽  
Ivo Sláma

Molar heat capacities and molar enthalpies of fusion of the solvates Zn(NO3)2 . 2·24 DMSO, Zn(NO3)2 . 8·11 DMSO, Zn(NO3)2 . 6 DMSO, NaNO3 . 2·85 DMSO, and AgNO3 . DMF, where DMSO is dimethyl sulfoxide and DMF is dimethylformamide, have been determined over the temperature range 240 to 400 K. Endothermic peaks found for the zinc nitrate solvates below the liquidus temperature have been ascribed to solid phase transformations. The molar enthalpies of the solid phase transformations are close to 5 kJ mol-1 for all zinc nitrate solvates investigated. The dependence of the molar heat capacity on the temperature outside the phase transformation region can be described by a linear equation for both the solid and liquid phases.


Author(s):  
Thomas Köllen ◽  
Susanne Kopf

AbstractSo far, management research on mechanisms of exclusion of employee groups has mainly applied constructs of racism to understanding issues of origin-based ostracism. This research has primarily focused on issues faced by employees whose heritage is markedly different from the heritage shared by the norm group in the given socio-cultural, linguistic, and geographical setting. Against this backdrop, the present study investigates how ostracism plays out when the heritages involved are similar, as exemplified by German employees in Austria. Study 1 examines the discursive production of Austrian stereotyping of Germans in the usage of different terms of reference for ‘Germans’ in Austrian discourse. A corpus analysis of online comments on newspaper sites highlights the implicit Austrian need for delineation against Germany. Study 2 analyzes Germans’ perception of Austrians’ exclusionary linguistic practices and how this impacts on their employment experience and turnover intention. A quantitative analysis of survey data from 600 German nationals employed in Austria reveals that the degree of exposure to these demarcating practices is associated with lower job satisfaction, a higher burnout level and an increase in turnover intention. This study is amongst the first to shed light on the central role of nationalism and national identities in organizational mechanisms of exclusion.


1994 ◽  
Vol 40 (134) ◽  
pp. 132-134
Author(s):  
R.E. Gagnon ◽  
C. Tulk ◽  
H. Kiefte

AbstractSingle crystals and bicrystals of water ice have been adiabatically pressurized to produce, and clearly illustrate, two types of internal melt figures: (1) dendritic figures that grow from nucleation imperfections on the specimen’s surface, or from air bubbles at grain boundaries, into the ice as pressure is elevated; and (2) compression melt fractures, flat liquid-filled disks, that nucleate at imperfections in the crystal and grow with the application of pressure eventually to sprout dendritic fingers at the periphery. The transparency of the ice permitted visualization of the growth and behavior of the figures, and this could be an important tool in understanding the role of phase transformations in deep-focus earthquakes. Correlation between figure size and pressure is noted for the first time.


2018 ◽  
Vol 60 (11) ◽  
pp. 1122-1129
Author(s):  
M. I. Tonkonog ◽  
K. A. Levin ◽  
A. S. Shabalin ◽  
V. A. Makarov ◽  
I. I. Fishman

2014 ◽  
Vol 611 ◽  
pp. 46-53 ◽  
Author(s):  
Ladislav Novotný ◽  
Vladimír Ivančo

In the paper the principle of welding simulation is presented and the methods of solution of phase transformation are described. The first part characterizes elementary equations of heat transient solution, boundary conditions during welding simulation (prescribing moving heat flux, convection, radiation). The methods of phase transformations’ solution are described for diffusion processes as well as diffusionless processes.


Author(s):  
R. J. Dennis ◽  
R. Kulka ◽  
O. Muransky ◽  
M. C. Smith

A key aspect of any numerical simulation to predict welding induced residual stresses is the development and application of an appropriate material model. Often significant effort is expended characterising the thermal, physical and hardening properties including complex phenomena such as high temperature annealing. Consideration of these aspects is sufficient to produce a realistic prediction for austenitic steels, however ferritic steels are susceptible to solid state phase transformations when heated to high temperatures. On cooling a reverse transformation occurs, with an associated volume change at the isothermal transformation temperature. Although numerical models exist (e.g. Leblond) to predict the evolution of the metallurgical phases, accounting for volumetric changes, it remains a matter of debate as to the magnitude of the impact of phase transformations on residual stresses. Often phase transformations are neglected entirely. In this work a simple phase transformation model is applied to a range of welded structures with the specific aim of assessing the impact, or otherwise, of phase transformations on the magnitude and distribution of predicted residual stresses. The welded structures considered account for a range of geometries from a simple ferritic beam specimen to a thick section multi-pass weld. The outcome of this work is an improved understanding of the role of phase transformation on residual stresses and an appreciation of the circumstances in which it should be considered.


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