What is Materials Science and Metallurgy?
Take a look around you. You’re probably inside a building made of concrete and cement, supported by columns of ultra-strong steel. You are probably viewing this website on a LED screen. LEDs(Light- emitting diodes) are basically semiconductors which are illuminated by the movement of electrons. This website is hosted on a computer somewhat different than yours, but all computers in the world (from your smartphones and gaming consoles to the huge Supercomputers used in NASA, CERN and other research organizations) are made of electrical components, which are made of semiconductor materials. To be very generic, the computing power of all these computers depends on the charge storage capacity and electrical conductance of the semiconductor materials.
Now go outside and again look around you. You would see cars, buildings, people wearing colorful clothes and carrying bags, some people staring intently into their smartphones, flickering traffic lights, airplanes soaring across the sky and many more. If you live by the coast, you may also see gigantic ships, the sheer size and grandeur of which makes you wonder at what human engineering can achieve. From people’s clothes to the largest ships and aeroplanes – what all these things have in common is that they are made of materials.
Everything that civilization consists of, is made of something. Archaeologists and anthropologists would classify different epochs of civilization by the materials they would use, like Bronze Age, Iron Age, Copper Age etc. The Industrial Age is also called Steel Age because of the invention and vast improvements of Steel. The results are what you now see around you – enormous skyscrapers, state of the art automotive, strong and magnificent bridges and structures etc. Owing to the growth and vast expanse of computing, the modern times could as well be called the Silicon Age.
Everything that you see around you can be classified into these 8 categories:
Metal – malleable, reflective, good conductor. They are used basically everywhere. Metallurgical engineering exclusively deals with metals and metal alloys.
Ceramics – non-metallic materials composed of inorganic molecules. Mostly oxides and nitride compounds. They have a huge range of applications, from Refractories(kiln linings, steel and glass making crucibles), Space Shuttle Programs, bomb and bullet protection, jet engine turbine blade coatings, nuclear fuel, mechanical bearing to disk brakes for cars and motorbikes, etc
Composites – mixtures of two or more materials, having superior properties to each of the constituent materials. They are extremely strong, but very light. They are used to make aerospace components (fuselages, propellers, tails, wings), military-civilian-sports vehicles, orthopedic surgery, sports equipment (baseball bats, tennis rackets)
Concrete – mixture of water, sand, gravel, crushed stone, and cement. Concrete is used to build houses and infrastructure like roads, dams, bridges, sidewalks etc.
Electrical/Optical Materials – These materials may be metals, ceramics or polymers. These materials are carefully formulated to control the amount of electricity or light which passes through them. Semiconductors are examples of electrical materials, they’re used to make transistors and chips. Optical materials include many ceramics and polymers.
Glass – hard, brittle, noncrystalline, more or less transparent substance. Glass is used in optical devices, electrical gadgets like your smartphones and tablet computers, buildings and architecture, etc.
Polymers/Plastics – composed of large molecular chains. Usually the long chains are formed by Carbon. The carbon atoms may be attached to other carbon, oxygen, nitrogen, and hydrogen atoms. Polymers may or may not have an orderly arrangement of atoms. Polymers are used in agriculture (improve aeration and promote plant growth), biomaterials (heart valve replacements and blood vessels), clothing, automobile parts, pipes, tanks, adhesives, insulation, sports equipment etc.
Wood – composite material made from lignin and cellulose.
However as a student of Materials Science and Engineering, you’d find that these frontiers are constantly being pushed and newer and better materials are being manufactured to improve everyday goods, and even expand their functionality.
Some modern material’s needs:
Engine efficiency increases at high temperatures: requires high temperature
Use of nuclear energy requires solving problem with residues, or advances in
nuclear waste processing.
Hypersonic flight requires materials that are light, strong and resist high
Optical communications require optical fibers that absorb light negligibly.
Civil construction – materials for unbreakable windows.
Structures: materials that are strong like metals and resist corrosion like
Basis of Materials Science:
The task of a materials scientist is to correlate the structure of a material with its properties. Once he/she does that, he/she then compares a material’s performance in various real life applications. The major determinants of a material’s structure (and hence, its properties) are its constituent chemical elements and how it has been processed.
Structure – materials scientists examine the structure of a material from the atomic scale to the macro scale. This examination is done by a process called Characterization. The different materials characterization techniques are X-Ray Diffraction, Raman Spectroscopy, Thermal analysis, Electron microscope analysis etc.
Crystallography – this is the science of atomic arrangement in crystalline solids. Physical properties are often controlled by crystal defects.
Synthesis and Processing – this involves the creation of a material with the desired micro/nanostructure. If you want to use a material in industry, you must find a cheap way of manufacturing it while sustaining and enhancing its desirable properties simultaneously. Hence, materials processing is a very crucial part of materials engineering.
Thermodynamics – this is the basis of treating general phenomena in materials science and engineering, such as chemical reactions, magnetism, polarizability and elasticity. It also helps to understand phase diagrams and phase equilibrium.
Kinetics – this is the study of the rate of reactions and how systems move towards or away from equilibrium. In materials science, kinetics deals with how materials change (moves from non- equilibrium to equilibrium state) in response to electro-magnetic fields, Diffusion is particularly important in kinetics, because this is the most common way in which materials change. Kinetics also tells us how microstructure changes with heat.
To summarize, Materials Science is an interdisciplinary field that grew out of physics, chemistry and engineering principles (electrical, mechanical, chemical). Materials Engineering is the application of Materials Science principles in industry to increase productivity, invent new functionalities and reduce cost of production. Materials Science and Engineering is the study of the building blocks that made civilization, and that will push us forward towards ever newer frontiers.