材料科学与工程概述(原文)matscience

Materials Science and Engineering Overview The Field - Preparation - Day In The Life - Earnings -

Employment - Industries - Development -

Career Path Forecast - Professional Organizations

Materials Science and Engineering (MSE) is a field of

engineering that encompasses the spectrum of materials types

and how to use them in manufacturing. Materials span the

range: metals, ceramics, polymers (plastics), semiconductors,

and combinations of materials called composites. We live in a

world that is both dependent upon and limited by materials.

Everything we see and use is made of materials: cars,

airplanes, computers, refrigerators, microwave ovens, TVs,

dishes, silverware, athletic equipment of all types, and even

biomedical devices such as replacement joints and limbs. All of these require materials specifically tailored for their application. Specific properties are required that result from carefully selecting the materials and from controlling the manufacturing processes used to convert the basic materials into the final engineered product. Exciting new product developments frequently are possible only through new materials and/or processing. New materials technologies developed through engineering and science will continue to make startling changes in our lives in the 21st century, and people in Materials Science and Engineering will continue to be key in these changes and advances. These engineers deal with the science and technology of producing materials that have properties and shapes suitable for practical use. Activities of these engineers range from primary materials production, including recycling, through the design and development of new materials to the reliable and economical manufacturing for the final product. Such activities are found commonly in industries such as aerospace, transportation, electronics, energy conversion, and biomedical systems. The future will bring ever-increasing challenges and opportunities for new materials and better processing. Materials are evolving faster today than at any time in history. New and improved materials are an "underpinning technology" - one which can stimulate innovation and product improvement. High quality products result from improved processing and more emphasis will be placed on reclaiming and recycling. For these many reasons, most surveys name the materials field as one of the careers with excellent future opportunities.

The Field

CD-ROMs, like everything around us, are made of materials. So are dessert plates, basketballs, car engines, telephones, and audiocassettes. Therefore the work done under the heading of Materials Science Engineering has an unprecedented impact on our quality of life. Although the field deals with materials, it encompasses an incredible diversity of topics and problems constituting the four elements of the field -- processing, structure, properties, and performance.

Materials

History is measured by innovations in materials. Developments in metals like iron and bronze enabled advances in civilization thousands of years ago, a synergy which continues today in the fiber optics that have created the World Wide Web and in the development of biomaterials that mimic living tissue. As you explore the field it may be useful to become familiar with some generic categories of materials.

Metals

Metals are materials that are normally combinations of "metallic elements". These

elements, when combined, usually have electrons that are non-localized and as a

consequence have generic types of properties. Metals usually are good conductors of heat and electricity. They are also quite strong but deformable and tend to have a

lustrous look when polished.

Ceramics

Ceramics are generally compounds between metallic and nonmetallic elements and

include such compounds as oxides, nitrides, and carbides. Typically they are insulating and resistant to high temperatures and harsh environments.

Plastics

Plastics, also known as polymers, are generally organic compounds based upon carbon and hydrogen. They are very large molecular structures. Usually they are low density

and are not stable at high temperatures.

Semiconductors

Semiconductors have electrical properties intermediate between metallic conductors

and ceramic insulators. Electrical properties are strongly dependent upon small

amounts of impurities.

Composites

Composites consist of more than one material type. Fiberglass, a combination of glass and a polymer, is an example. Concrete and plywood are other familiar composites.

Many new combinations include ceramic fibers in metal or polymer matrix. Processing

Processing refers to the way in which a material is achieved. Advances in technology have made it possible to create a material atomic layer by atomic layer. There are four general categories which may be useful to know: solidification processing, powder processing, deposition processing, and deformation processing.

Solidification Processing

Most metals are formed by creating an alloy in the molten state, where it is relatively

easy to mix the components. This process is also utilized for glasses and some

polymers. Once the proper temperature and composition have been achieved, the melt is cast. Castings can be divided into two types, depending on the subsequent

processing steps. The first type is shape casting, which takes advantage of the fluidity of liquid metal to form complex shapes directly. Because of the complexity of their part geometries, these castings generally cannot be worked mechanically to a significant

degree. Therefore any changes in microstructure or properties must either be achieved first during solidification or through subsequent heat treatments.

Powder Processing

Powder processing involves consolidation, or packing, of particulate to form a `green

body'. Densification follows, usually by sintering. There are two basic methods of

consolidating powders: either dry powder can be compacted in a die, a process known as dry-pressing, or the particles can be suspended in a liquid and then filtered against the walls of a porous mold in a process known as slip-casting or filter pressing. Bulk

ceramics are usually processed in powder form since their high melting points and low formability prohibit other types of processing. Metals and polymers can also be

processed from powders.

Deposition Processing

Deposition processing modifies a surface chemically, usually by depositing a chemical vapor or ions onto a surface. It is used in semiconductor processing and for decorative or protective coatings. Vapor source methods require a vacuum to transport the

gaseous source of atoms to the surface for deposition. Common vapor sources are

thermal evaporation (similar to boiling water to create steam), sputtering (using

energetic ions to bombard a source and create the gas state), or laser light (ablates, or removes, atoms from surface to create the gaseous state). Other sources use carrier media such as electrochemical mixtures (ions in a solution transported by an electrical field to the surface for depositions) or spray coating (ions or small particles transported by gases, liquids, and/or electrical field).

Deformation Processing

One of the most common processes is the deformation of a solid to create a desired

shape. A large force is generally used to accomplish the deformation, and many

techniques heat the material in order to reduce the force necessary to deform it.

Sometimes a mold is used to define the shape. Forging, an old method that heated the metal and deformed the metal by hammer blows is still used today, albeit with multi-ton hammers. Rolling to reduce the thickness of a plate is another common process. Some glasses when heated can be formed with tools or molds. Other common methods, like drilling to make holes, or milling, are machining versions of the deformation process. Structure

Structure refers to the arrangement of a material's components from an atomic to a macro scale. Understanding the structure of a substance is key to understanding the state or condition of a material, information which is then correlated with the processing of the material in tandem with its properties. Understanding these relationships is an intrinsic part of materials science engineering, as it allows engineers to manipulate the properties of a material. Properties

Does a material need to be strong and heat-resistant, yet lightweight? Whether you're talking about a fork or the space shuttle, products have specific requirements which necessitate the use of materials with unique properties. Materials engineers must frequently reconcile the desired properties of a material with its structural state to ensure compatibility with its selected processing. Typical properties of interest may be classified into:

Mechanical Properties: Tensile strength, fracture toughness, fatigue strength, creep strength, hardness

Electrical Properties: Conductivity or resistivity, ionic conductivity, semiconductor

conductivity (mobility of holes and electrons)

Magnetic Properties: Magnetic susceptibility, Curie Temperature, Neel Temperature, saturation magnetization

Optical and Dielectric Properties: Polarization, capacitance, permittivity, refractive

index, absorption

Thermal Properties: Coefficient of thermal expansion, heat capacity, thermal

conductivity

Environmental Related Properties: Corrosion behavior, wear behavior Performance

The evaluation of performance is an integral part of the field. The analysis of failed products is often used to obtain feedback on processing and its control as well as to assist in the initial selection of the material and in the stages of processing. Testing also ensures that the product meets performance requirements. In many products the control of its processing is closely associated with some property test and/or a structural characterization.

Preparation

Preparation for a career in materials engineering can begin as early as

high school, and need not be limited to a course of `materials' study.

There are many kinds of programs, degrees, and disciplines that will

enable you to pursue a career in the field.

Pre-College

It is highly recommended that while in high school you take the

maximum amount of college preparatory mathematics, laboratory

sciences, and English offered. If choices are possible, those courses

highly dependent upon knowledge and reasoning should take

precedence over courses in which the emphasis is on manual skill.

Students should try to take all the physical sciences and mathematics

courses offered at their school. In addition, students should take

advantage of all available opportunities to develop their communication

skills. Study of a language other than English is desirable. Talk to your guidance counselor about requirements at the university of your choice

College Programs

Most major universities have academic BS degree granting programs in one of the specialty areas of Materials Science and Engineering. The majority of undergraduate programs provide a survey across the spectrum of materials. Other programs focus in one particular class of materials like Ceramics, Metallurgy, or Polymers.

A few universities only have graduate programs. Graduate programs are open to people with bachelors degrees in the field as well as those from other more general areas of science and

engineering. Specific areas of expertise in each program are dependent upon the faculty in that program. The average program is staffed by 15 faculty members. Programs range in faculty size from less than ten members to near forty. No single program covers the entire field due its breadth and the typically modest number of faculty members.

Accredited Programs

Those interested in a career in materials engineering should consider reviewing engineering programs that are accredited by the Accreditation Board for Engineering and Technology, Inc. (ABET). ABET accreditation is based on an evaluation of an engineering program's student achievement, program improvement, faculty, curricular content, facilities, and institutional commitment. The following is a partial list of universities offering accredited degree programs in materials engineering, including materials, ceramic, and metallurgical programs.

Materials Programs

?The University of Akron

?University of Alabama at Birmingham

?Alfred University

?Arizona State University

?University of Arizona

?Auburn University

?Brown University

?California Polytechnic State University, San Luis Obispo

?University of California, Davis

?University of California, Irvine

?University of California, Los Angeles

?Carnegie Mellon University

?Case Western Reserve University

?University of Cincinnati

?Colorado School of Mines

?Cornell University

?Drexel University

?University of Florida

?Georgia Institute of Technology

?University of Illinois at Urbana-

Champaign

?Illinois Institute of Technology

?Iowa State University

?The Johns Hopkins University

?University of Kentucky

?Lehigh University

?University of Maryland College Park

?Massachusetts Institute of Technology

?Michigan State University

?Michigan Technological University

?University of Michigan

?University of Minnesota-Twin Cities

?Montana Tech of the University of

Montana

?New Mexico Institute of Mining and

Technology

?North Carolina State University at Raleigh ?Northwestern University

?The Ohio State University Ceramic Programs

?Alfred University

?Clemson University

?University of Missouri-Rolla

?Pennsylvania State Univers ity

?Rutgers, The State University

of New Jersey

Metallurgical Programs

?The University of Alabama

?Colorado School of Mines

?University of Idaho

?University of Missouri-Rolla

?Montana Tech of the University of Montana

?University of Nevada-Reno

?The Ohio State University

?University of Pittsburgh

?South Dakota School of Mines and Technology

?University of Texas at El Paso

?University

?Pennsylvania State University

?University of Pennsylvania

?University of Pittsburgh

?Purdue University at West Lafayette

?Rensselaer Polytechnic Institute

?San Jose State University

?University of Tennessee at Knoxville

?University of Texas at El Paso

?University of Utah

?Virginia Polytechnic Institute and State

University

?Washington State University

?University of Washington

?Winona State University

?University of Wisconsin-Madison

?University of Wisconsin-Milwaukee

?Wright State University

Coursework

A materials program serves a dual purpose: it provides

technical information and instills a thought process

characteristic of the engineering discipline. All programs

integrate the four elements of the field (properties,

structure, processing, and performance) through the

several classes of materials (ceramics, electronic

materials, metals, polymers, composites). Specialized

curricula synthesize one class of materials with the

elements of the field, in a Ceramic Engineering or Metallurgical Engineering program, for example. In most programs, however, a core curriculum is incorporated with courses addressing the scientific principles relating to the properties and behavior of materials, as well as the structure (atomic configurations), characterization, and processing of materials. Engineering design courses focus on the performance of materials in applications and emphasize devising new materials, components, systems, or processes to meet particular objectives. Most engineering programs develop from a mathematical base coupled with aspects of chemistry or physics. MST, however, builds almost equally upon chemistry and physics and includes an increasing influence of biology. Communications, social issues, and the humanities are also incorporated in order to provide individuals the requisite breadth to be able to place technical problems in the context of tomorrow’s world.

Concentrations

Degrees are granted in several specializations and concentrations, including materials, metals, minerals, ceramics, and polymers. Within these study programs, one can emphasize areas such as processing, structure-property relationships, electronic properties, and chemical and environmental effects.

Graduate School

Many students continue their studies to earn an advanced degree, a master's (MS) degree or a doctoral (Ph.D./D.Sc.) degree. They do this either directly after earning the BS degree or after some work experience. An MS degree generally can be earned within two years after the BS degree. The doctoral degree, which typically involves four plus years of study and research beyond the BS degree, is usually completed by those interested in careers in research and/or teaching. Depending on an individual's career goals, the BS degree

may also be followed by study in such fields as business

administration, management, medicine, and law.

Study Abroad

Studying abroad can be an exciting and rewarding experience.

Materials Science & Engineering careers may take you overseas or

at least offer you the opportunity to work with international

corporations. Information on studying abroad may be obtained from

university counselors. For more information, visit:

o Institute of International Education: https://www.360docs.net/doc/082069291.html,

o Resource for Study Abroad: https://www.360docs.net/doc/082069291.html,

o Council of International Educational Exchange: https://www.360docs.net/doc/082069291.html,

o Association for International Practical Training: https://www.360docs.net/doc/082069291.html,

Day in the Life

From cellular phones to artificial hip joints to lightweight bicycles,

materials engineers work to develop products that improve lives.

Materials engineers bring advances in the auto, aerospace,

construction, manufacturing, electronics, computer, and

telecommunications industries by developing new or improved metals,

plastics, ceramics, semiconductors and composites. They work to

increase the strength of steel, toughen ceramics, lower the cost of

composites and make faster computer circuits. Materials are involved

in almost every engineering product, and materials engineers are

needed to select the best material, improve its properties, lower its

processing cost and increase its durability.

Career Tracks

There can be many tracks within a career. A materials engineer might

begin in a technical area such as manufacturing or research and

development, and then move into a management, sales, marketing, or a consulting role, depending on interest and ability.

Teamwork & Environment

In a manufacturing operation most tasks are conducted by cross-functional teams of people. Materials engineers are generally part of a support group integral to these teams for various functions -- from design concept through manufacturing processes to final product evaluations.

Skills

In addition to the technical and problem-solving skills requisite for a career in the field, the so-called `soft skills' will play a significant role in your success. Leadership abilities, teamwork, communication skills, flexibility, goal orientation, as well as the capacity for organization, all figure prominently in a career.

Alternatives

Because of their training and skills, materials engineers make strong candidates for jobs not traditionally associated with engineering: sales, training, law, medicine, insurance, real estate, publishing, finance, technical service, and government.

Diversity

Opportunities exist for a wide range of people with a spectrum

of backgrounds. A recent survey shows a changing distribution

of people in the field over the past twenty years. Much of this

change was the result of people becoming aware of the

opportunities in the field.

Organizational Size

Each work environment is unique. Factors like a company's size may impact your career. Over half of the people polled in a recent survey of the field work in large companies (more than 1000 people). However, a growing number of materials engineers are finding positions in small companies.

Earnings

Earnings for engineers vary significantly by specialty, industry,

and education. Even so, as a group, engineers earn some of

the highest average starting salaries among those holding

bachelor's degrees.

Starting Salary

According to a 2005 salary survey by the National Association

of Colleges and Employers, bachelor's degree candidates in

materials engineering received starting salary offers averaging $50,982 a year.

Variation in median earnings and in the earnings distributions for engineers in the various branches of engineering also is significant. For aerospace engineers, earnings distributions by percentile in May 2004 are shown in the following tabulation.

Specialty 10%25%50%75%

90%

$101,120 Materials $44,130$53,510$67,110$83,830

Employment

According to the U.S. Bureau of Labor Statistics, materials engineers

held about 21,000 jobs in 2004. This represents 1.5% of the 1.4

million jobs held by engineers in the U.S. in 2004.

Materials engineers are involved in the development, processing, and

testing of the materials used to create a range of products, from

computer chips and television screens to golf clubs and snow skis.

They work with metals, ceramics, plastics, semiconductors, and

composites to create new materials that meet certain mechanical,

electrical, and chemical requirements. They also are involved in

selecting materials for new applications. Materials engineers have

developed the ability to create and then study materials at an atomic

level, using advanced processes to replicate the characteristics of

materials and their components with computers. Most materials engineers specialize in a particular material. For example, metallurgical engineers specialize in metals such as steel, and ceramic engineers develop ceramic materials and the processes for making ceramic materials into useful products such as glassware or fiber optic communication lines. Employers

The following is a partial list of employers of materials scientists and engineers:

?3M Company

?Advanced Magnetics, Inc.?Advanced Micro Devices.?AK Steel Corp.

?Alcan Aluminum

?ALCOA

?Allegheny Ludlum Corp.?Alliant Techsystems ?Amcast

?American Superconductor ?Applied Materials

?Argonne National Laboratory ?ASARCO, Inc.

?Babcock & Wilcox

?BASF Corporation

?Battle Mountain Gold Company ?Bayer Corp.

?Beaver Valley Alloy Foundry ?Bechtel

?BF Goodrich

?Black & Decker

?Boeing Company ?Brookhaven National Lab.?Cabot Corporation ?Chevron Chemical ?Chrysler Corporation ?Cincinnati Milacron, Inc.?CMI International

?Conoco ?Georgia Pacific

?Hewlett Packard

?IBM

?Ingersoll-Rand

?Intel Corporation ?International Paper

?ITT

?Johnson Controls, Inc.?Kaiser Aluminum

?KB Alloys Inc.

?Kennecott Corp.

?Logan Clay Products

?Los Alamos National Lab ?LTV Steel

?Lucent Technologies ?Michelin

?Microsoft Corporation

?Mobil Corporation

?Motorola

?Nalco Chemical

?National Science Foundation ?National Starch & Chemical Co.?Nissan Motor Corporation USA ?Norsk Hydro Aluminum ?Nucor Corp.

?PPG Industries

?Procter & Gamble

?Sherwin-Williams ?Specialized Bicycle Components

?Corning Incorporated ?Crucible Materials Corp.?CSM Industries, Inc.?Cypress Semiconductor ?Dalton Foundries ?Deere & Company, Inc.?Dow Chemical ?Eastman Chemical Co.?Eastman Kodak

?Eaton Corp

?EI DuPont

?Exxon Chemical Company ?Flint Ink Corporation ?FMC Corporation

?Ford Motor Company ?General Electric ?General Motors ?Sun Microsystems ?Sundstrand Aerospace ?Taylor Made Golf Co.?Tensar Corporation ?Texas Instruments, Inc.?Timken Co.

?United States Mint ?United Technologies ?W.L. Gore

?Wabash Alloys

?Wahl Refractories ?Waupaca Foundry Inc.?Westinghouse ?Wheeling-Pittsburgh Steel ?Wolvering Tube Co.?Xerox

Industries

Virtually all industries demand people with backgrounds in

materials engineering. These people may be monitoring

impurities in steel destined for an assembly line, shrinking the

size of circuits to improve the reliability of a pager, or designing

new materials for a missile casing. Industries may employ

materials engineers to reduce the overall weight of a vehicle,

remove limitations in power plants, or research product failures

for a liability suit.

Sectors

There are four general sectors of industry that employ materials engineers:

Primary Materials Producing

These companies provide basic materials to other companies who manufacture a

component for a product or the end product itself. Examples are steel companies, glass companies, polymer powder producing companies, etc. Typically these are relatively

large organizations. This sector comprises a small number of companies that support a much larger number of manufacturing businesses.

Manufacturing

These companies produce a component or end product using materials from Primary

Producing companies. This sector includes a large number of companies ranging in size from a few to thousands of employees. This sector represents many different industries: transportation, electrical/electronics, machinery, computers/office, biomaterials, durable goods, and non-durable goods.

Service

Companies in this sector provide support for others. Employers include consulting firms, research and development organizations, construction companies, utilities, engineering services, communications companies, and research groups.

Other

Educational institutions, government, legal organizations, healthcare, business services, finance, insurance, and wholesale/retail are some of the other employers of materials

engineers.

Professional Development

Learning is a life-long endeavor. Advances in technology are

perpetually changing the tools of materials engineering, so

maintaining your technical competence will be a constant pursuit. It

will also be important to continue developing communication skills.

Actively pursuing professional development opportunities in and out of

the work environment can expand your abilities and career options.

Making Yourself Marketable

Maintaining technical competence is important, but the development

of other capacities (i.e., communications skills, networking, mentoring)

is just as critical. By honing these crafts you will become more

marketable.

Registration

Being a registered professional engineer is important in those areas of the field with direct public impact, such as in consulting firms. Take the Fundamentals of Engineering (FE) Exam when a senior or immediately following graduation; this exam is a prerequisite for sitting for the PE Exam. After four years of professional experience, contact your State Board. Each board generally has a packet of information which outlines the steps to be taken by engineers to become a registered Professional Engineer. This includes the requirements engineers must fulfill to qualify as a candidate to take the Principles and Practices Examination and rules while taking the examination. Further Resources:

National Society of Professional Engineers: https://www.360docs.net/doc/082069291.html,

National Council of Examiners for Engineering and Surveying: https://www.360docs.net/doc/082069291.html,

Value of Networking

The opportunity to meet and discuss materials successes and challenges with one's peers is invaluable toward not only project success, but also personal success. Sharing information and ideas is generally beneficial to both parties and is a hallmark of a successful engineer. Networking is the single most important cited resource for people to obtain new positions. Continuing Education

While you will perhaps seldom find yourself in a classroom, you must remain current in your chosen specialty. Possible forms of continuing education include: reading technical journals and publications, attending conferences, workshops or training courses, and obtaining membership in a professional society.

Career Path Forecast

According to the U.S. Department of Labor, Bureau of Labor

Statistics, materials engineers are expected to have

employment growth about as fast as the average for all

occupations through 2014.

Although many of the manufacturing industries in which

materials engineers are concentrated are expected to

experience declining employment, materials engineers still will

be needed to develop new materials for electronics,

biotechnology, and plastics products.

Growth should be particularly strong for materials engineers working on nanomaterials and biomaterials. As manufacturing firms contract for their materials engineering needs, employment growth is expected in professional, scientific, and technical services industries. Professional Organizations

Professional organizations and associations provide a wide

range of resources for planning and navigating a career in

materials science and engineering. These groups can play a

key role in your development and keep you abreast of what is

happening in your industry. Associations promote the interests

of their members and provide a network of contacts that can

help you find jobs and move your career forward. They can

offer a variety of services including job referral services,

continuing education courses, insurance, travel benefits,

periodicals, and meeting and conference opportunities. The following are several professional societies serving the materials science and engineering community. A broader list of professional associations is also available at https://www.360docs.net/doc/082069291.html,/assoc.htm.

ASM International: https://www.360docs.net/doc/082069291.html,

ASM International is a society whose mission is to gather, process and disseminate technical information. ASM fosters the understanding and application of engineered materials and their research, design, reliable manufacture, use and economic and social benefits. This is accomplished via a unique global information-sharing network of interaction among members in forums and meetings, education programs, and through publications and electronic media. The American Ceramic Society: https://www.360docs.net/doc/082069291.html,

The American Ceramic Society (ACerS) is a 100-year-old non-profit organization that serves the informational, educational, and professional needs of the international ceramics community. The Society's more than 7,500 members comprise a wide variety of individuals and interest groups that include engineers, scientists, researchers, manufacturers, plant personnel, educators, students, marketing and sales professionals, and others in related materials disciplines.

The Materials Research Society: https://www.360docs.net/doc/082069291.html,

The Materials Research Society (MRS) is an organization of materials researchers from academia, industry, and government that promotes communication for the advancement of interdisciplinary materials research to improve the quality of life. Founded in 1973, MRS now consists of more than 13,000 members from the United States -- as well as over 50 other countries. The Society is different from that of single discipline professional societies because it encourages communication and technical information exchange across the various fields of science affecting materials.

The Minerals, Metals & Materials Society: https://www.360docs.net/doc/082069291.html,

The Minerals, Metals & Materials Society (TMS) is a professional organization that encompasses the entire range of materials and engineering, from minerals processing and primary metals production to basic research and the advanced applications of materials. Included among its nearly 10,000 professional and student members are metallurgical and materials engineers, scientists, researchers, educators, and administrators from more than 70 countries on six continents.

Additional Resources:

?American Institute of Mining, Metallurgical, and Petroleum Engineers: https://www.360docs.net/doc/082069291.html, ?American Society for Testing and Materials: https://www.360docs.net/doc/082069291.html,

?American Welding Society: https://www.360docs.net/doc/082069291.html,

?Association of Iron & Steel Engineers: https://www.360docs.net/doc/082069291.html,

?International Metallographic Society: https://www.360docs.net/doc/082069291.html,

?Iron & Steel Society: https://www.360docs.net/doc/082069291.html,

?NACE International: https://www.360docs.net/doc/082069291.html,

?Society for Mining, Metallurgy and Exploration: https://www.360docs.net/doc/082069291.html,

?Society of Automotive Engineers: https://www.360docs.net/doc/082069291.html,

?Society of Petroleum Engineers: https://www.360docs.net/doc/082069291.html,

?The Electrochemical Society: https://www.360docs.net/doc/082069291.html,

?The Metallurgical Society of CIM: https://www.360docs.net/doc/082069291.html,