Unit I. The subject of material science

МАТЕРИАЛОВЕДЕНИЕ

Учебное пособие

 

 

Волгоград 2017

 

 

ББК Ш 143.21-92

Рецензенты:

 

д-р филол. наук, проф. каф. иностранных языков ВолгГТУ,

профессор В. И. Карасик;

канд. пед. наук, доцент кафедры социально-гуманитарных дисциплин и педагогики АНО ВПО ЦС РФ «Российский университет кооперации» Волгоградский кооперативный институт (филиал) Т.Г. Йованович.

 

Печатается по решению редакционно-издательского совета

Волгоградского государственного технического университета

Материаловедение: учебное пособие по развитию навыков чтения и перевода для студентов старших курсов профиля «Технология конструкционных материалов». Английский язык / С.В.Баталин, И.С. Бессарабова, Н.И. Кохташвили, Т. Н. Синенко; ВолгГТУ. – Волгоград, 2017 - с.

ISBN ….- -

 

Целью методического пособия является развитие у бакалавров и магистров навыков чтения и понимания аутентичных англоязычных текстов по материаловедению с целью формирования навыков уверенного понимания технической литературы и использования полученных навыков в дальнейшей профессиональной деятельности.

В пособии использованы оригинальные тексты, отобран соответствующий языковой и речевой материал, разработана система упражнений для закрепления специализированной терминологической лексики и развития навыков чтения и перевода по тематике, связанной с описанием процессов и различными этапами технологической обработки металлов.

Формирование навыков чтения и перевода специальной технической литературы реализуется в контексте коммуникативного подхода на основе современных достижений методики обучения иностранным языкам для специальных целей. Методическое пособие предназначено для бакалавров и магистрантов технических специальностей, специализирующихся на технологиях обработки металлов.

 

Библиография: назв.

ISBN

© Волгоградский государственный

технический университет, 2016

© С. В. Баталин, И.С. Бессарабова,

Н. И. Кохташвили, Т. Н. Синенко, 2017

 

ПРЕДИСЛОВИЕ

Данное учебное пособие предназначено для бакалавров 1 – 4 курсов и магистрантов технических специальностей, подготовка которых связана с изучением такой дисциплины, как материаловедение. Предполагается, что обучающиеся владеют английским языком на уровне Pre-Intermediate (ниже среднего) и Intermediate (средний). Целью пособия явялется развитие профессиональной языковой компетенции, совершенствование навыков самостоятельного чтения и перевода оригинальной технической англоязычной литературы по дисциплине.

Пособие состоит из четырех разделов (Sections), тематически соответствующих основным разделам курса материаловедения. В каждом разделе содержатся списки терминов, используемых для описания материаловедческих понятий, а также аутентичные тексты по данной тематике. Тексты снабжены системой упражнений, предназначенных для закрепления терминологической лексики, а также для развития навыков делового общения. Кроме того, включены вопросы и упражнения, направленные на повторение и отработку различных грамматических аспектов на материале изучаемой лексики.

Данное пособие полностью соответствует Государственному образовательному стандарту программы по дисциплине "Иностранный язык профессионального общения (английский)".

SECTION I

Unit I. THE SUBJECT OF MATERIAL SCIENCE

Part I

1. Learn the words:

to involve	влечь за собой; подразумевать
discovery	открытие
design	проектирование
solid-state physics	физика твердого тела
research	иследование
major	главный
create	создавать
pressing problem	актуальная проблема
currently	в настоящее время
due to	в результате
available	имеющийся в наличии
thus	таким образом
to affect	оказывать влияние
significant	значительный
processing	обработка; переработка
to influence	влиять
property	свойство
performance	эксплуатационные свойства
relationship	связь
forensic engineering	инженерно-техническая экспертиза
failure analysis	анализ дефектов
to investigate	исследовать
to intend	намереваться
to cause	являться причиной
application	применение
area	область
damage	ущерб

2. Guess the meaning of the following words and word combinations:

Materials science; emphasis; origin; analytical thinking; engineering; major; to affect; limit; specific; future; breakthrough; performance; to advance; determinant; constituent; incident; accident; chemical element; component; kinetics; thermodynamics; metallurgy; to govern; nanotechnology; structure.

3. Identify the part of speech and translate the words:

To discover, discovery, discoverer; research, researcher; science, scientist, scientific; observation, to observe, observer; recognize, recognition; create, creation, creature, creator; available, availability; current, currently, currency; emphasis, emphasize; performance, performer, performing (arts); to relate, relative, relation, relationship, correlation; to fail, failure; to investigate, investigation; to operate, operation; various, variety, to vary, variable; to apply, application, applicable, applicant; to determine, determinant, determination; to process, process, processing; to characterize, characterization; to intend, intention.

4. Match the words with their definitions:

to involve	To plan
discovery	a quality or power that a substance, plant etc has
to cause	to influence
application	having an important effect or influence, especially on what will happen in the future
damage	to include or affect someone or something
to intend	to make something happen, especially something bad
property	a fact or thing that someone finds out about, when it was not known about before
to affect	physical harm that is done to something or to a part of someone’s body, so that it is broken or injured
significant	the practical purpose for which amachine, idea etc can be used, or a situation when this is used

Text A.

Rate – скорость

Equilibrium - равновесие

Text B.

Chemical kinetics is the study of the rates at which systems that are out of equilibrium change under the influence of various forces. When applied to materials science, it deals with how a material changes with time (moves from non-equilibrium to equilibrium state) due to application of a certain field. It details the rate of various processes occurring in materials including shape, size, composition and structure. Diffusion is important in the study of kinetics as this is the most common mechanism by which materials undergo change. Kinetics is important in processing of materials because, among other things, it details how the microstructure changes with application of heat.

Part II

1. Learn the words:

to mention	упоминать
length	длина
scale	размер; шкала
to deal with	иметь дело с
to arise (arose, arisen)	возникать; появляться
way	способ
to bond	связывать; сцеплять
behaviour	поведение
prepared surface	обработанная поверхность
thin foil	тонкая фольга
to reveal	раскрывать
magnification	увеличение
to be broadly classified	классифицировать в общих четрах
strength	прочность
toughness	жесткость; ударная вязкость
ductility	вязкость
hardness	твердость
corrosion resistance	коррозионная устойчивость
high/low temperature	высокая/низкая температура
wear resistance	износоустойчивость
to manufacture	изготавливать
perfect	совершенный
to contain	содержать
precipitate	выделившаяся фаза
grain boundary	граница зерна
impossible	невозможный
interstitial atom	межузельный атом
vacancy	вакансия (в кристаллической решетке)
substitutional atom	атом замещения
to reveal	раскрывать
naked eye	невооруженный глаз

2. Guess the meaning of the words and word combinations:

Component; atomic scale; diffraction with X-rays; neutron; macro scale; energy dispersive spectroscopy; chromatography; thermal analysis; electron microscope analysis; atomic structure; molecule; crystal; angstrom; scale; nanostructure; an object; to agglomerate; microstructure; ceramic; fundamental, polymeric, composite.

3. Identify the part of speech and translate the words:

To examine, examination, exam, examiner; important, importance; to arrange, arrangement; to form, formation; to define, definition, definite; to classify, classifying, classification; influence, influenced; to manufacture, manufacturer, manufacturing; to contain, container; vacant, vacancy, vacation; possible, impossible; substitute, substitution, substitutional; defect, defective; to appear, to disappear, appearance, disappearance; strength, strong, strengthen; prepare, preparation, prepared.

Text А. Structure

As mentioned above, structure is one of the most important components of the field of materials science. Materials science examines the structure of materials from the atomic scale, all the way up to the macro scale. Characterization is the way materials scientists examine the structure of a material. This involves methods such as diffraction with X-rays, electrons, or neutrons, and various forms of spectroscopy and chemical analysis such as Raman spectroscopy, energy-dispersive spectroscopy (EDS), chromatography, thermal analysis, electron microscope analysis, etc.

Structure is studied at various levels. Atomic structure deals with the atoms of the materials, and how they are arranged to give molecules, crystals, etc. Much of the electrical, magnetic and chemical properties of materials arise from this level of structure. The length scales involved are in angstroms. The way in which the atoms and molecules are bonded and arranged is fundamental to studying the properties and behavior of any material. Nanostructure deals with objects and structures that are in the 1—100 nm range. In many materials, atoms or molecules agglomerate together to form objects at the nanoscale. This causes many interesting electrical, magnetic, optical, and mechanical properties. Microstructure is defined as the structure of a prepared surface or thin foil of material as revealed by a microscope above 25× magnification. It deals with objects from 100 nm to a few cm. The microstructure of a material (which can be broadly classified into metallic, polymeric, ceramic and composite) can strongly influence physical properties such as strength, toughness, ductility, hardness, corrosion resistance, high/low temperature behavior, wear resistance, and so on. Most of the traditional materials (such as metals and ceramics) are microstructured.

The manufacture of a perfect crystal of a material is physically impossible. For example, a crystalline material will contain defects such as precipitates, grain boundaries (Hall–Petch relationship), interstitial atoms, vacancies or substitutional atoms. The microstructure of materials reveals these defects, so that they can be studied. Macro structure is the appearance of a material in the scale millimeters to meters—it is the structure of the material as seen with the naked eye.

Text В.

Thermodynamics

Thermodynamics deals with heat and temperature and their relation to energy and work. It defines macroscopic variables, such as internal energy, entropy, and pressure that partly describe a body of matter or radiation. It states that the behavior of those variables is subject to general regularities that are common to all materials, not the peculiar properties of particular materials. These general regularities are expressed in the four laws of thermodynamics. Thermodynamics describes the behavior of the body, not the microscopic behaviors of the very large numbers of its microscopic components, such as molecules. The behavior of these microscopic particles is described by, and the laws of thermodynamics are based on statistical mechanics. The study of thermodynamics is fundamental to materials science. It forms the foundation to study general phenomena in materials science and engineering, including chemical reactions, magnetism, polarizability, and elasticity. It also helps in the understanding of phase diagrams and phase equilibrium.

Part III

1. Learn the words:

tool	инструмент
shape	форма
reflect	отражать
further	далее
to occur	происходить
condition	условие
diffraction pattern	дифракционная диаграмма
sample	образец
to exhibit	демонстрировать
powder	порошок
conventional	обычный
alloy	сплав
mixture	смесь
distinction	отличие
to apply	применять
concept	понятие
ordering	упорядоченность (структуры кристаллов)
to display	показывать, демонстрировать
completely	полностью
degree	степень
to possess	обладать
to combine	сочетать
confidently	уверенно

2. Guess the meaning of the words:

To control; orientation, amorphous, element, triangular, amorhous.

3. Identify the part of speech and translate the words:

Crystal, crystalline, crystallize; reflect, reflection, reflective; occur, occurrence; regular, irregular, regularity, regulation; mixture, mix; apply, application; to extend; extension, extensive, extended; advantage, disadvantage; complete, completely, completion, completed; to combine, combination, combinatory, combined; describe, description, descriptive; confident, confidence, confidently.

Text A.

Crystallography

Crystallography is the science that examines the arrangement of atoms in crystalline solids. Crystallography is a useful tool for materials scientists. In single crystals, the effects of the crystalline arrangement of atoms is often easy to see macroscopically, because the natural shapes of crystals reflect the atomic structure. Further, physical properties are often controlled by crystalline defects. The understanding of crystal structures is an important condition for understanding crystallographic defects. Mostly, materials do not occur as a single crystal, but in polycrystalline form, i.e., as an aggregate of small crystals with different orientations. Because of this, the powder diffraction method, which uses diffraction patterns of polycrystalline samples with a large number of crystals, plays an important role in structural determination.

Most materials have a crystalline structure, but some important materials do not exhibit regular crystal structure. To obtain a full understanding of the material structure and how it relates to its properties, the materials scientist must study how the different atoms, ions and molecules are arranged and bonded to each other. When classifying a material it is useful to decide whether it is crystalline (conventional metals and alloys), non-crystalline (glasses) or a mixture of these two types of structure. The critical distinction between the crystalline and non-crystalline states of matter can be made by applying the concept of ordering. Polymers display varying degrees of crystallinity, and many are completely non-crystalline. Glass, some ceramics, and many natural materials are amorphous, not possessing any long-range order in their atomic arrangements. The study of polymers combines elements of chemical and statistical thermodynamics to give thermodynamic and mechanical descriptions of physical properties.

5. Join the halves of the sentences in the columns:

Mostly, materials	do not exhibit regular crystal structure.
Most materials have a crystalline structure, but some important materials	can be made by applying the concept of ordering.
The critical distinction between the crystalline and non-crystalline states of matter	is an important condition for understanding crystallographic defects.
The understanding of crystal structures	do not occur as a single crystal, but in polycrystalline form

6. Answer the questions:

Vital - жизненно важный

Require – требовать

Text B

Synthesis and processing involves the creation of a material with the desired micro-nanostructure. From an engineering standpoint, a material cannot be used in industry if no economical production method for it has been developed. Thus, the processing of materials is vital to the field of materials science.

Different materials require different processing or synthesis methods. For example, the processing of metals has historically been very important and is studied under the branch of materials science named physical metallurgy. Also, chemical and physical methods are used to synthesize other materials such as polymers, ceramics, thin films, etc. As of the early 21^st century, new methods are being developed to synthesize nanomaterials such as graphene.

PART IV

1. Learn the words:

stainless steel	нержавеющая сталь
cast iron	чугун
quantity	количество
low/mid/high carbon steel	низко-средне-высокоуглеродистая сталь
carbon	углерод
level	уровень
tensile strength	прочность на разрыв
amount	количество
(to be) present	присутствовать
content	содержание
by weight	в весовом отношении
heat treatment	термообработка
quenching	закалка
tempering	отпуск
however	однако
to increase	увеличить
ratio	отношение
to provide	обеспечивать
shielding	защита; экранирование

2. Guess the meaning of the following words and word combinations:

Proportion, chromium, nickel molybdenum, titanium, copper, magnesium, aluminum, chemical reactivity, electrolytic extraction, strength-to-weight ratio; automotive.

3. Identify the part of speech and translate the words:

Value, valuable; proportion, proportional; significant, significance, significantly, insignificant; require, requirement, required.

Text A.

Metal alloys

The study of metal alloys is a significant part of materials science. Of all the metallic alloys in use today, the alloys of iron (steel, stainless steel, cast iron, tool steel, alloy steels) make up the largest proportion both by quantity and commercial value. Iron alloyed with various proportions of carbon gives low, mid and high carbon steels. An iron carbon alloy is only considered steel if the carbon level is between 0.01% and 2.00%. For the steels, the hardness and tensile strength of the steel is related to the amount of carbon present, with increasing carbon levels also leading to lower ductility and toughness. Heat treatment processes such as quenching and tempering can significantly change these properties however. Cast iron is defined as an iron–carbon alloy with more than 2.00% but less than 6.67% carbon. Stainless steel is defined as a regular steel alloy with greater than 10% by weight alloying content of Chromium. Nickel and Molybdenum are typically also found in stainless steels.

Other significant metallic alloys are those of aluminum, titanium, copper and magnesium. Copper alloys have been known for a long time (since the Bronze Age), while the alloys of the other three metals have been relatively recently developed. Due to the chemical reactivity of these metals, the electrolytic extraction processes required were only developed relatively recently. The alloys of aluminum, titanium and magnesium are also known and valued for their high strength-to-weight ratios and, in the case of magnesium, their ability to provide electromagnetic shielding. These materials are ideal for situations where high strength-to-weight ratios are important, such as in the aerospace industry and automotive engineering applications.

5. Translate the sentence and pay attention to the way of avoiding repetition:

PART V

Subsection 1

1. Learn the words:

consequently	следовательно
stress	напряжение
to incur	подвергнуться; нести
ultimate strength	предел прочности
to refer to	ссылаться на; относиться к;
pound per square inch (psi)	фунт на квадратный дюйм
unit stress	удельное напряжение
rupture	разрыв
tensile test	испытание на разрыв
failure	отказ; разрушение
fracture	разрушение
to depend	завесить
adherence	адгезия, сцепление
strain	механическая деформация
to distort	деформировать
dimension	размер
elasticity	упругость
removal	удаление
to be subjected to	быть подвергнутым
to release load	снять нагрузку
permanently	постоянно

2. Guess the meaning of the words and word combinations:

External, internal, deformation, to resist, to act, unit force, unit stress, elastic, original.

3. Identify the part of speech and translate the words:

Attention, attentive, attentively, inattentive; to exhibit, an exhibit, exhibition; structure, structural; to refer, reference, referential; failure, to fail; fracture, fraction; to depend; dependence; quantity, quantitavely; to distort, distortion; to measure, measurement; dimension, dimensional; to regain, to gain; permanent, permanently

Text А.

Text B.

Within the limit of elasticity the ratio of stress to strain is known as the modulus of elasticity (i. e. measure of elasticity). The modulus of elasticity expresses the stiffness of a material. For steel and most metals this is a constant property very little affected by heat-treatment, hot or cold working, or the actual ultimate strength of the metal. Their moduli of elasticity show that, when equal-size bars of steel and aluminium are subjected to the same load, the resulting elastic deformation in the aluminum will be almost three times as great as in the steel bar.

Subsection B

1. Learn the words:

stress-strain curve	кривая напряжение - деформация
to decrease	уменьшать
mild steel	мягкая сталь
normalized steel	нормализованная сталь
specimen	образец
to support	поддерживать
cross-sectional area	площадь поперечного сечения
tensile strength	прочность на разрыв
a piece	деталь
ductility	вязкость
yield point	предел текучести
capacity	способность; возможность; качество
to denote	означать
obviously	очевидно
elongation	удлинение
reduction of area	уменьшение площади поперечного сечения (при обработке изделия)
value	значение; величина
tension test	испытание на растяжение/разрыв
gradually	постепенно
impact test	испытание на удар
malleability	ковкость; пластичность
to permit	разрешать
to roll	прокатывать
to hammer	ковать
a thin sheet	тонкий лист (металла)
lead	свинец
tin	олово
to lack	не хватать
to be drawn	волочить (о проволоке)
brittleness	хрупкость
fatigue failure	усталостное разрушение
tension	напряжение; растяжение
indentation	отпечаток (при испытании на твердость)
to scratch	царапать

2. Guess the meaning of the words and word combinations:

visible, permanent, reverse, elastic limit, opposite, term,, to confuse, synonymously, alternation, to produce, compression, statically; cold-worked steel

3. Identify the part of speech and translate the words:

Repeat, repetition, repeated; alternation, to alternate, alternating; to produce, production, productive, productivity, product, producer.

Text A.

SECTION II

Part I

1. Learn the words:

to refer	относиться
separate	отдельный
identifiable	опознаваемый
substance	вещество
to exist	существовать
applicable to	применимый к
to provide	предоставлять
convenient	удобный
in addition to	в дополнении к
iron	железо
refractory oxide silica	огнеупорный оксид кремния
tridymite	тридимит
cristobalite	кристобалит
silica glass	кварцевое стекло
molten silica	расплавленный кремнезем
glass-reinforced polymer	армированный стекловолокном полимер
fibreglass	стекловолокно
bounding surface	ограничивающая поверхность
contiguous phase	непрерывная фаза
structural disturbances and imperfections	структурные нарушения и недостатки
an oxide solid solution	твердый раствор оксида
by convention	условно
voids	пустоты
rapid cooling rates	скорость быстрого охлаждения
equilibrium	равновесие
annealing of metals and alloys	отжиг металлов и сплавов
structural heterogeneity	структурная неоднородность
high silica content	высокое содержание кремнезема
boric oxide	оксид бора
a porous siliceous matrix	пористая кремниевая матрица
withstand quenching	выдерживать закалку

 

2. Guess the meaning of the following words and word combinations:

Microdefects; grain boundaries; metastable condition; ‘triggering’ process; nonequilibrium; scientific difficulty; high temperature applications; to be heat-treated; separation of two phases; electron microscopy; boron-rich phase; skeletal structure; a low linear coefficient; thermal expansion; iced water; maximum service temperature.

3. Identify the part of speech and translate the words:

To separate, separation, separately; to identify, identification, identifier; to exist, existence, existing; to apply, application, applicable; to provide, provider, providing; to differentiate, differentiation, differential; to imply, implied, implicit; to reveal, revealing; to surround, surrounded, surroundings; consolidate, consolidation; to refer, reference; to express, expression, expressed; to add, additional, addition; to comprise, comprising; to disturb, disturbance, disturbed.

4. Match the words with their definitions:

the concept of a phase	чистый металл
crystalline and non-crystalline materials	тепловая активация
way of expressing	термостойкий
exist as a liquid or vapour	вязкость
a pure metal	процесс изготовления
thermal activation	существовать в виде жидкости или пара
thermal-shock resistant	способ выражения
viscosity	кристаллические и некристаллические материалы
fabrication process	концепция фазы

 

Text A

The concept of a phase

The term ‘phase’ refers to a separate and identifiable state of matter in which a given substance may exist. Being applicable to both crystalline and noncrystalline materials, its use provides a convenient way of expressing a material’s structure. Thus, in addition to the three crystalline forms, the element iron may exist as a liquid or vapour, giving five phases overall. Similarly, the important refractory oxide silica is able to exist as three crystalline phases, quartz, tridymite and cristobalite, as well as a non-crystalline phase, silica glass, and as molten silica. Under certain conditions, it is possible for two or more different phases to co-exist. The glass-reinforced polymer (GRP) known as Fibreglass is an example of a two-phase structure. When referring to a particular phase in the structure of a material, we imply a region comprising a large number of atoms (or ions or molecules) and the existence of a bounding surface which separates it from contiguous phases. Local structural disturbances and imperfections are disregarded. Thus, a pure metal or an oxide solid solution are each described, by convention, as single-phase structures even though they may contain grain boundaries, concentration gradients (coring) and microdefects, such as vacancies, dislocations and voids. Industrial practice understandably favours relatively rapid cooling rates, frequently causing phases to exist in a metastable condition. Some form of ‘triggering’ process, such as thermal activation, is needed before a metastable phase can adopt the stable, or equilibrium, state of lowest energy (e.g. annealing of metals and alloys). These two features, structural heterogeneity on a micro-scale and nonequilibrium, do not give rise to any untoward scientific difficulty.

The production of the thermal-shock resistant known as Vycor provides an interesting example of the potential of phase control. Although glasses of very high silica content are eminently suitable for high temperature applications, their viscosity is very high, making fabrication by conventional methods difficult and costly. This problem was overcome by taking advantage of phase separation in a workable silica containing a high proportion of boric oxide. After shaping, this glass is heat-treated at a temperature of 500–600°C in order to induce separation of two distinct and interpenetrating glassy phases. Electron microscopy reveals a wormlike boron-rich phase surrounded by a porous siliceous matrix. Leaching in hot acid dissolves away the former phase, leaving a porous silica-rich structure. Consolidation heat-treatment at a temperature of 1000°C ‘shrinks’ this skeletal structure by a remarkable 30%. This product has a low linear coefficient of thermal expansion and can withstand quenching into iced water from a temperature of 900°C, its maximum service temperature.

 

5. Open the brackets and put the predicate in the correct form, translate the sentences:

The Phase Rule.

Equation – уравнение

Text B

For a given metallic or ceramic material, there is a theoretical condition of equilibrium in which each constituent phase is in a reference state of lowest energy. The independent variables determining this energy state, which are manipulated by scientists and technologists, are composition, temperature and pressure. The Phase Rule derived by Willard Gibbs from complex thermodynamical theory provides a device for testing multi-phase (heterogeneous) equilibria and deciding the number of variables (degrees of freedom) necessary to define the energy state of a system. Its basic equation, P+F=C+2, relates the number of phases present at equilibrium (P) and the number of degrees of freedom (F) to the number of components (C), which is the smallest number of substances of independently-variable composition making up the system. For metallic systems, the components are metallic elements: for ceramics, the components are frequently oxides (e.g. MgO, etc.).

 

Part II

 

1. Learn the words:

two-phase equilibria	двухфазные равновесия
solid solubility	твердая растворимость
nickel	никель
copper	медь
the intervening alloys	промежуточные сплавы
to freeze	замораживать
liquidus and solidus	ликвидус и солидус
to consider	рассматривать
solidification	затвердевание
alloy	сплав
amount	количество
manganese	марганец
ductile	пластичный
to resist	оказывать сопротивление
water treatment	очистка воды
complete	полный, абсолютный
to coincide	совпадать
fulcrum	точка опоры
Lever Rule	правило рычага
to restrict, to confine	ограничивать
adjacent to	примыкающий к
beryllium	бериллий
curving	изогнутый
solvus	сольвус
increase	увеличение
to dissolve	растворять(ся)
to quench	гасить, охлаждать

 

2. Guess the meaning of the following words and word combinations:

Metallic and ceramic systems; similarities and differences; atomic (ionic) diameter; a univariant phase; corrosion; visualize; fractions; precipitation-hardening.

3. Identify the part of speech and translate the words:

To extend, extended, extending; to illustrate, illustrated, illustration; abrupt, abruptly, abruptness; to consider, consideration; to equilibrate, equilibration; to resist, resistance, resistant; to complete; completely, completeness; to coincide, coincidental, coincidentally; to represent, representation, representative; to derive, derivative, derivation; to restrict, restriction, restrictive; to confine, confined, confinement; to preserve, preservation.

4. Match the words with their definitions:

extended and limited solid solubility	химическая и пищевая промышленность
binary phase diagram	средний состав сплава
solid solution	горизонтальные соединительные линии
melting points of the pure metals	растворимая медь
chemical and food processing	точки плавления чистых металлов
average composition of the alloy	бесконечное число
infinite number	твердый раствор
horizontal tie-lines	двоичная фазовая диаграмма
solvent copper	расширенная и ограниченная растворимость в твердом состоянии

 

Text A

Two-phase equilibria

Extended and limited solid solubility. Solid solubility is a feature of many metallic and ceramic systems, being favoured when the components have similarities in crystal structure and atomic (ionic) diameter. Such solubility may be either extended (continuous) or limited. The former case is illustrated by the binary phase diagram for the nickel–copper system in which the solid solution extends from component to component. In contrast to the abrupt (congruent) melting points of the pure metals, the intervening alloys freeze over a range of temperatures which is associated with a univariant two phase (α + liquid) field. This ‘pasty’ zone is located between two lines known as the liquidus and solidus. The phase diagrams for Ni–Cu and MgO–FeO systems are similar in form.

Let us consider the very slow (equilibrating) solidification of a 70Ni–30Cu alloy. A commercial version of this alloy, Monel, also contains small amounts of iron and manganese. It is strong, ductile and resists corrosion by all forms of water, including sea-water (e.g. chemical and food processing, water treatment). An ordinate is erected from its average composition on the base line. Freezing starts at a temperature T1. A horizontal tie-line is drawn to show that the first crystals of solid solution to form have a composition α1. When the temperature reaches T2, crystals of composition α2 are in equilibrium with liquid of composition L2. Ultimately, at temperature T3, solidification is completed as the composition α3 of the crystals coincides with the average composition of the alloy. It will be seen that the compositions of the α - phase and liquid have moved down the solidus and liquidus, respectively, during freezing.

Each tie-line joins two points which represent two phase compositions. One might visualize that a two phase region in a binary diagram is made up of an infinite number of horizontal (isothermal) tie-lines. Using the average alloy composition as a fulcrum (x) and applying the Lever Rule, it is quickly possible to derive mass ratios and fractions. In most systems, solid solubility is far more restricted and is often confined to the phase field adjacent to the end-component. A portion of a binary phase diagram for the copper–beryllium system, which contains a primary, or terminal, solid solution, is shown in Figure 3.13. Typically, the curving line known as the solvus shows an increase in the ability of the solvent copper to dissolve beryllium solute as the temperature is raised. If a typical ‘beryllium–copper’ containing 2% beryllium is first held at a temperature just below the solidus (solution-treated), water-quenched to preserve the α-phase and then aged at a temperature of 425°C, particles of a second phase (γ) will form within the α –phase matrix because the alloy is equilibrating in the (α+ γ) field of the diagram. This type of treatment, closely controlled, is known as precipitation-hardening.

 

5. Fill in the prepositions (as, of, by, for, to, in) where necessary:

1. To provide this criterion it is necessary to consider a second important property ___ state known ___ the entropy.

2. This type ___ treatment, closely controlled, is known ___ precipitation-hardening.

3. Solid solubility is a feature ___ many metallic and ceramic systems.

4. The former case is illustrated ___ the binary phase diagram ___ the nickel–copper system.

5. In contrast ___ the abrupt (congruent) melting points ___ the pure metals, the intervening alloys freeze over a range of temperatures.

6. One might visualize that a two phase region ___ a binary diagram is made up ___ an infinite number ___ horizontal (isothermal) tie-lines.

6. Join the halves of the sentences in the columns:

Solid solubility is	the binary phase diagram for the nickel–copper system.
The former case is illustrated by	a feature of many metallic and ceramic systems.
The compositions of the α - phase and liquid have	derive mass ratios and fractions.
It is quickly possible to	moved down the solidus and liquidus, respectively, during freezing.

 

7. Answer the questions:

What does the solvus show?

Criteria for equilibrium.

3. The concept of free energy.

Make sure that you know the following words and word combinations:

Enthalpy - энтальпия (термодинамическое свойство вещества)

Text B

Every material in a given state has a characteristic heat content or enthalpy, H, and the rate of change of heat content with temperature is equal to the specific heat of the material measured at constant pressure. A knowledge of the quantity H is clearly important to understand reactions but it does not provide a criterion for equilibrium, nor does it determine when a phase change occurs, as shown by the occurrence of both exothermic and endothermic reactions. To provide this criterion it is necessary to consider a second important property of state known as the entropy, S. In statistical terms S may be regarded as a measure of the state of disorder of the structure, but from classical thermodynamics it may be shown that for any material passing through a complete cycle of events = 0, where dQ is the heat exchanged between the system and its surroundings during each infinitesimal step and T is the temperature at which the transfer takes place.

 

Part III

 

1. Learn the words:

coring	отбор керна, взятие керновой пробы
composition	состав
to maintain	поддерживать
to adjust	регулировать
rapid	быстрый
grain	зерно
core	ядро
unduly	чрезмерно
outer regions	внешние области
etch	гравировать; травить (на металле, стекле)
polished specimen	полированный образец
dendritic segregation	дендритная сегрегация
chill-cast ingots	литейные слитки
extensive	экстенсивный, обширный
to impair	ухудшать
properties	свойства
annealing	отжиг
localized fusion	Локализованное слияние
practicable	реальный
advantage	преимущество
to intermingle	смешиваться
to reduce	уменьшaть
to accelerate	ускорять
to promote	содействовать
subsequent	последующий
equiaxed	равноосный

 

2. Guess the meaning of the following words and word combinations:

Microsegregation; freezing process; atomic migration; diffusion; composition gradients; non-uniform solid solution; cored grain; to cold-work; to be broken up by deformation; recrystallization; hot-working.

3. Identify the part of speech and translate the words:

To refer, reference, referred; to progress, progressive, progressively; consequent, consequently, consequences; to continue, continuous, continuously; to adjust, adjustment, adjustable; relative, relatively; rapid, rapidly, rapidity; to allow, allowance; extensive, extensively; to produce, producer, produced; to impair, impaired, impairment; to homogenize, homogenizer, homogenized; to select, selective, selection; advantage, advantageous; to promote, promoter, promoted; subsequent, subsequently; to eliminate, elimination, eliminated.

4. Match the words with their definitions:

liquid phase	температура плавления
industrial conditions	физическая и химическая гетерогенность
the cooling rate of the solid phase	выбранный с осторожностью
complete elimination of differences in composition	богатый металлом с низкой температурой плавления
physical and chemical hetereogeneity	полное устранение различий в составе
melting point	неравновесные скорости охлаждения
non-equilibrium cooling rates	скорость охлаждения твердой фазы
selected with care	промышленные условия
rich in low melting point metal	жидкая фаза

 

Text A

Coring

It is now possible to consider microsegregation in more detail. Referring again to the freezing process for a Ni–Cu alloy, it is clear that the composition of the α-phase becomes progressively richer in copper and, consequently, if equilibrium is to be maintained in the alloy, the two phases must continuously adjust their compositions by atomic migration. In the liquid phase such diffusion is relatively rapid. Under industrial conditions, the cooling rate of the solid phase is often too rapid to allow complete elimination of differences in composition by diffusion. Each grain of the α-phase will thus contain composition gradients between the core, which will be unduly rich in the metal of higher melting point, and the outer regions, which will be unduly rich in the metal of lower melting point. Such a non-uniform solid solution is said to be cored: etching of a polished specimen can reveal a pattern of dendritic segregation within each cored grain.

The faster the rate of cooling, the more pronounced will be the degree of coring. Coring in chill-cast ingots is, therefore, quite extensive. The physical and chemical hetereogeneity produced by non-equilibrium cooling rates impairs properties.

Cored structures can be homogenized by annealing. For instance, an ingot may be heated to a temperature just below the solidus temperature where diffusion is rapid. The temperature must be selected with care because some regions might be rich enough in low melting point metal to cause localized fusion. However, when practicable, it is more effective to cold-work a cored structure before annealing.

This treatment has three advantages. First, dendritic structures are broken up by deformation so that regions of different composition are intermingled, reducing the distances over which diffusion must take place. Second, defects introduced by deformation accelerate rates of diffusion during the subsequent anneal. Third, deformation promotes recrystallization during subsequent annealing, making it more likely that the cast structure will be completely replaced by a generation of new equiaxed grains. Hot-working is also capable of eliminating coring.

 

5. Translate the sentences, pay attention to the modal verbs:

Dendritic coring.

Cellular microsegregation.

3. Constitutional undercooling.

Make sure that you know the following words and word combinations:

dilute alloy - разбавленный сплав

the slope of the curve for actual temperature - наклон кривой для фактической температуры

Text B

In the case of a solid solution, we have seen that it is possible for solvent atoms to tend to freeze before solute atoms, causing gradual solute enrichment of an alloy melt and, under non-equilibrium conditions, dendritic coring (e.g. Ni–Cu). When a very dilute alloy melt or impure metal freezes, it is possible for each crystal to develop a regular cell structure on a finer scale than coring. The thermal and compositional condition responsible for this cellular microsegregation is referred to as constitutional undercooling. Suppose that a melt containing a small amount of lower-m.p. solute is freezing. The liquid becomes increasingly enriched in rejected solute atoms, particularly close to the moving solid/liquid interface. The variation of liquid composition with distance from the interface is shown in Figure 3.14a. There is a corresponding variation with distance of the temperature TL at which the liquid will freeze, since solute atoms lower the freezing temperature. Consequently, for the positive gradient of melt temperature T shown in Figure 3.14b, there is a layer of liquid in which the actual temperature T is below the freezing temperature TL: this layer is constitutionally undercooled. Clearly, the depth of the undercooled zone, as measured from the point of intersection, will depend upon the slope of the curve for actual temperature, i.e. GL D dT/dx. As GL decreases, the degree of constitutional undercooling will increase.

Figure 3.14. Variation with distance from solid/liquid interface of (a) melt composition and (b) actual temperature T and freezing temperature TL.

 

 

Part IV

 

1. Learn the words:

three-phase equilibria	трехфазные равновесия
the eutectic reaction	эвтектическая реакция
fixed values	фиксированные значения
lead	свинец
tin	олово
straight	прямой
ternary	тройной
in accordance with	в соответствии с
equation	уравнение
approximately	примерно
ratio	соотношение
enriched	обогащенный
to remain	оставаться
to comprise	включать
to deduce	выводить, делать вывод
to consist of	состоять из
precipitate	осадок, оставлять осадок
to obtain	получать
to superimpose < 12345678910Следующая ⇒ Поделиться с друзьями: Таксономические единицы (категории) растений: Каждая система классификации состоит из определённых соподчиненных друг другу... Индивидуальные и групповые автопоилки: для животных. Схемы и конструкции... Семя – орган полового размножения и расселения растений: наружи у семян имеется плотный покров – кожура... Эмиссия газов от очистных сооружений канализации: В последние годы внимание мирового сообщества сосредоточено на экологических проблемах...  © cyberpedia.su 2017-2024 - Не является автором материалов. Исключительное право сохранено за автором текста. Если вы не хотите, чтобы данный материал был у нас на сайте, перейдите по ссылке: Нарушение авторских прав. Мы поможем в написании вашей работы! 0.211 с.