Materials science studies the properties of matter to solve science and engineering problems. It uses applied physics and chemistry. Supersmall nanotechnology has got attention in recent years. There are many inventions of new material. Work on why structures fail or break down is very important to engineering.
History
The important material of a given era is often its defining point. Examples are the Stone Age, Bronze Age, and Iron Age.
Materials science originally studied ceramics and metallurgy. These ancient crafts make materials science one of the oldest forms of engineering and applied science. A major breakthrough in the understanding of materials occurred in the late 19th century, when the American scientist Josiah Willard Gibbs showed that the physical properties of a material were related to its atomic structure. As the phases changed, so did the physical properties of the material.
Important elements of modern materials science are a product of the space race: the understanding and engineering of the metallic alloys, and silica and carbon materials, used in the construction of space exploration vehicles.
Materials science is now linked to the development of plastics, semiconductors, ceramics, polymers, magnetic materials, medical implant materials and biological materials.
The material scientist/engineer also deals with the extraction of materials and their conversion into useful forms. So, ingot casting, foundry techniques, blast furnace extraction, and electrolytic extraction are all part of the required knowledge of a metallurgist/engineer. Often the presence, absence or variation of minute quantities of secondary elements and compounds in a bulk material will have a great impact on the final properties of the materials produced, for instance, steels are classified based on 1/10 and 1/100 weight percentages of the carbon and other alloying elements they contain. Thus, the extraction and purification techniques employed in the extraction of iron in the blast furnace will have an impact of the quality of steel that may be produced.
Cause of failures
The study of disasters in the 19th and 20th century led to some important discoveries. A.A. Griffith (1893–1963) discovered that real materials never get near their theoretical strength. This was a groundbreaking discovery which led to changes in many industries. As an example, steel gets almost 1/10th of its theoretical strength, but most solids are 100 to 1000 times weaker than expected.
Griffith's insights were developed further by J.E. Gordon (1913–1998). Gordon said that all simple solids are by their nature brittle. Toughness – resistance to fracture – has to be designed into materials. The usual way is to add other material to the pure substance. This makes its structure more complex, and that makes it less likely to fail. A good example is bulletproof glass, where a plastic layer stuck to glass make it many times stronger than either material would be separately. The personal armour based on Kevlar is another example. Biological materials have this feature naturally. Bones do bend a little before they reach breaking point, and tree trunks also have some "give".
Metal alloys
The industrial study of metal alloys is a large 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. Increasing carbon levels leads 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 also found in stainless steels.