MATERIALS SCIENCE

Materials science and engineering is a field broadly based in chemistry, physics, and the engineering sciences. The field is concerned with the design, manufacture, and use of all classes of materials (including metals, ceramics, semiconductors, polymers, and biomaterials), and with the environmental, health, economic, and manufacturing issues relating to materials. Materials science and engineering is a field critical to future economic and environmental well-being.
Materials science emphasizes the study of the structure of materials and of processing-structure-property relations in materials. It is the physics and chemistry of real materials. Almost all the properties of importance to an engineer are structure-sensitive—that is, they can be modified in significant ways by changing the chemical composition, the arrangement of the atoms or molecules in crystalline or amorphous configurations, or the size, shape, and orientation of the crystals or other macroscopic units of a solid. To understand how the useful properties of a material can be modified, it is necessary to understand the relationships between structure and properties and how the structure can be changed and controlled by the various chemical, thermal, mechanical, or other treatments to which a material is subjected during manufacture and in use. The fundamental understanding of materials developed through materials science has replaced empiricism as the basis for discovery of new materials. Whole classes of new materials such as semiconductors, superconductors, and some high-temperature alloys have their roots in modern materials science.
All recent achievements in materials have depended as much on advances in materials engineering as they have on materials science. When developing processes for preparation and production of materials, and when designing materials for specific applications, the materials engineer must have a grasp of the modern engineering sciences, including heat and mass transfer and chemical kinetics. He or she must also have a proper concern for economic, social, and environmental factors. Materials processing is a major part of materials engineering. Improved performance of materials depends directly on advances in processing. There are also many examples of challenging engineering problems in reducing the cost and improving the productivity of industrial processing of materials. The department has strong academic and research activities in all aspects of the processing of materials.
The links between materials engineering and materials science are very strong, and the two activities are interwoven in the department. There are some subjects that all students of materials should know: thermodynamics, kinetics, and certain aspects of solid mechanics, physics, and chemistry. Core subjects in these areas are provided at the undergraduate and graduate levels. In addition, subjects covering a wide variety of topics, from solid-state physics to the analysis of materials systems, are offered. By selecting appropriate subjects, the student can follow many different paths through the science and engineering of materials, with emphasis on engineering, science, or a mixture of the two.
Materials science and materials engineering disciplines seek to identify and understand the principles and phenomena that are basic to all materials. Many large industries today manufacture
products containing a great variety of different materials, and their materials engineers must acquire a working understanding of the basic behavior of all of them. However, there also are many large industries in which a single class of material (e.g., steel, polymers, glasses) is manufactured and processed, and their materials experts must have a knowledge of various aspects of the science and engineering of one class of material. Thus, lecture and lab subjects are provided in the department that enable a student to specialize in the science and engineering of ceramics, electronic materials, metals, polymers, or biomaterials.
Materials engineers and materials scientists, whether generalists or specialists in a particular class of material, are in continually high demand by industry and government for jobs in research, development, production, and management. They find challenging opportunities in a wide variety of important positions in operations, development, and research in the fast-growing electronics industry, in aerospace, in consumer industries, in biomaterials and medical industries, and in the basic materials preparation and producing industries.
Archaeology and Archaeological Science
The principles of materials science and materials engineering have particular relevance to the study of archaeological materials. Laboratory investigation of ancient and pre-industrial artifacts of metal, ceramic, stone, cloth and other materials enables archaeologists to reconstruct the materials technologies behind the design and production of objects in prehistory. The Center for Archaeological Materials is developing what might be called the materials science of material culture, exploring the relations between ancient people and their material world.
Archaeology is the systematic study of humanity in the past, concerned with reconstructing the environments in which people lived and the ecological systems in which they functioned. Encompassing the study of ancient technologies and other human activities, as well as peoples' social organization, religious beliefs, and every aspect of human culture, archaeology covers all of human history, from the time of the earliest human beings up to the present.
Because archaeology is so broad in scope and the data on which it relies derive primarily from field survey and excavations, a range of disciplines provides its foundation. Geology, anthropology, materials science, art history, and biology are among these fundamental fields. Archaeological science represents an approach to archaeology that utilizes modern science and engineering principles and methods to tackle pressing archaeological issues—for example, reconstructing time, place, and human ecologies of the past, or determining the materials technologies that transform natural materials into cultural objects.
MIT's archaeology education programs reflect particular strength in archaeological science research. The Bachelor of Science in Archaeology and Materials as recommended by the Department of Materials Science and Engineering derives from the focus on archaeological materials research within the Department of Materials Science and Engineering and the Center for Materials Research in Archaeology and Ethnology (CMRAE). This curriculum is unique within university departments of anthropology, archaeology, and engineering.

Materials science is an interdisciplinary field involving the properties of matter and its applications to various areas of science and engineering. This science investigates the relationship between the structure of materials and their properties. It includes elements of applied physics and chemistry, as well as chemical, mechanical, civil and electrical engineering. With significant media attention to nanoscience and nanotechnology in the recent years, materials science has been propelled to the forefront at many universities, sometimes

Introduction to Materials Science

"Materials are the stuff from which all things are made, be they mundane household utensils or sophisticated integrated circuits that drive all of our modern technological society" (TMS Career Resource Center, n.d.). "Materials Science encompasses the study of the structure and properties of any material, as well as using this body of knowledge to create new types of materials, and to tailor the properties of a material for specific uses. The field encompasses the spectrum of materials: metals, ceramics, polymers (plastics), semiconductors, and combinations of materials called composites" (Iowa State University, Department of Materials Science and Engineering 2001).
A very comprehensive description of the field of materials science and engineering is contained in the report "Materials Science and Engineering for the 1990s" prepared by the National Research Council's Committee on Materials Science and Engineering and published by the National Academy Press. Many materials scientists consider this to be a landmark report that has fueled considerable activity in research and development.
In 1999, the National Research Council Committee on Science & Engineering published another report "Materials Science and Engineering: Forging Stronger Links to Users." "Materials are the foundation and fabric of manufactured products. In fact, many leading commercial products and military systems could not exist without advanced materials and many of the new products critical to the nation's continued prosperity will come only through the development and commercialization of new materials. Thus, the field of materials science and engineering (MS&E) affects quality of life, industrial competitiveness, and the global environment."
Materials science heavily relies on physics, chemistry, other engineering fields such as mechanical and electrical engineering. Physical properties of materials are usually the deciding factor in choosing which materials should be used for a particular application. This involves looking at many factors such as: material composition and structure (chemistry), fracture and stress analysis (mechanical engineering), conductivity (electrical engineering), and optical and thermal properties (physics) to name a few. It also involves processing and production methods. Research in this area involves many peripheral areas including: crystallography, microscopy, mineralogy, photonics, and powder diffraction.

Exploring Materials Engineering

Metals and Alloys
If there is a typical engineering material that is associated in the public's mind with modern engineering practice, it is structural steel. This versatile construction material has several characteristics, or properties, that we consider metallic: (1) It is strong and can be readily formed into practical shapes. (2) Its extensive, permanent derformability, or ductility, is an important asset in permitting small amounts of yielding to sudden and severe loads. Many Californians have been able to observe moderate earthquake activity that leaves windows (of relatively brittle glass) cracked while steel support framing still functions normally. (3) A freshly cut steel surface has a characteristic metallic luster, and (4) a steel bar shares a fundamental characteristic with other metals: it is a good conductor of electrical current. Although structural steel is an especially common example of metals for engineering, a little thought produces numerous others [such as gold, platinum, lead and tin].

An alloy is a metal composed of more than one element. Engineering alloys include the cast-irons and steels, aluminum alloys, magnesium alloys, titanium alloys, nickel alloys, zinc alloys and copper alloys. For example, brass is an alloy of copper and zinc.
Taken from Introduction to Materials Science for Engineers, James F. Shackelford, Prentice Hall, Inc., New Jersey.
For more information on ferrous and non-ferrous metals and alloys, try this terrific MatSci and Engineering multi-media source.

Rarely do we find metallic elements in the `free' state. For example, consider native silver. Silver has been mined for eons and has always been popular in jewelry and for coinage. Only in the past hundred years however, has the demand for silver been so great. The reason for this demand is the use of silver in the photography industry, which takes advantage of silver's reactivity to light. Native Silver is rare and much silver is produced from silver-bearing minerals such as prousite, pyrargyrite, galena, etc. Specimens of Native Silver usually consist of wires that are curved and intertwined together, making an inspiring mineralogical curiosity. The reference source URL is a commercial supplier of mineral specimens. The image has Copyright ©1995,1996 by Amethyst Galleries, Inc


Society gets its metals from an ore, not from the natural element found in nature. Ores are often a combination of the metallic element and a non-metallic element. Consider, for example, Galena. Galena, PbS, is a common and popular mineral for rock hounds. Its characteristic cubes, distinctive cleavage and high density make it easy to identify and a favorite in high school geology labs. The structure of Galena is identical to that of halite, NaCl. The two minerals have the same crystal shapes, symmetry and cleavage. Some Galena may contain up to 1% silver in place of lead. The large volume of Galena that is processed for lead produces enough Silver as a by product in the production of Galena, the leading ore of Silver. The reference source URL is a commercial supplier of mineral specimens.

Shown on the left is the basic oxygen furnace used in the production of steel. Other steel production images are also available at this URL from Mittal Steel Company (formally, Inland Steel). For additional information on the making of steel, visit either of the following web pages: The Steel Society; or 'What's a Matter-U".

The basic oxygen furnace is just one method for producing steel. One way to make something useful is to pour the liquid metal directly into a crucible or mold and let it solidify. However, there are alternative processes such as the condensation of evaporated metallic elements; or the consolidation of micron-size particles! Some of these alternate processes are explored in the companion web page, AltProcess.htm
Here is where the metal aluminum, once 'won' from the earth, finds useful application. The aluminum alloy used in the production of beverage cans contains manganese and is highly hardenable. This means that when worked (or hammered!), the aluminum becomes harder or 'more resistant' to further deformation. The all aluminum-can is one of the most convenient and cost-effective containers ever developed for delivering beverages to consumers. If you would like to know how a beverage can is made from aluminum plate more than one-foot thick, I invite you to explore the following web pages. Discover just how amazing the aluminum beverage can really is. The reference source URL is The Aluminum Association.

Here is a close-up of the rocker assembly on a mountain bike. The reference source URL is Marin Bikes. If you would like to know more about the materials selection options for making a bicycle frame, please link to either of the following: Technical White Paper; or, the Career Resource Center for Materials Science & Engineering web pages on material aspects of the Bicycle. Another interesting component of the bicycle, usually made from a metallic alloy, is the spoke. The Web Pages of Belgian spoke manufacturer Sapim provide some insight to producing super lightweight, bladed spokes. For example, the small CX-Ray blades, of extremely high tensile strength (due to a special forging process), cut wind resistance markedly. A materials engineer (or mechanical engineer with materials expertise) would be involved with the following issues regarding the design and fabrication of advanced bicycle spokes:
• what alloy should be used?
• what are the fabrication steps to make this unique blade-shape?
• at what times and temperatures should the alloy be heat-treated?
• what are the appropriate surface-finish operations?
• what fatigue life is predicted for the spoke?
• do mechanical tests confirm strength and fatique life requirements?
The complexity of the design and selection of metals and alloys used in a high-temperature, aggressive environment is illustrated in this image (left). I believe this is a heat exchanger, perhaps in a petro-chemical plant. I found this image while doing a search for NDI (Non-Destructive Inspection) information, so the source is not directly relevant to the metals and alloys web pages. Nevertheless, I could not resist including it! The reference URL is Q.A.T.E., a Australasian quality assurance and testing engineering firm which manufacturers and resales NDI products.

There is a class of alloys called shape memory alloys. These alloys provide the engineer a means of restoring a bent metal wire to some trained alternate shape. These SMA's have applications ranging from frames for optical glasses to repair parts for the human body. For example, fine NiTi (containing approximate equal parts of nickel and titanium) shape memory or superelastic wires can be woven into cylindrical shapes for various applications. One such application is vascular stents to reinforce blood vessels in the human body. The stent is crushed and inserted through a cannula into the proper location in the blood vessel. Upon warming above its transformation temperature, the stent returns to its trained cylindrical shape and provides reinforcement to the walls of the blood vessel. If you would like to see a stent in-service in a blood vessel, go to the Biomaterials link on these pages. If you would like to know more about shape memory alloys, go to the web pages of Johnson-Mathis, the source of the image.
By the way, how do you think the common coin is made? This is a common metal device familiar to us all. Consider; what metal(s) and alloy(s) do you think are used in the fabrication of a dime? This is an excellent topic to search on the Internet. How is a dime fabricated? The process is termed 'coining' if this will help.