Malleable A temporary shape change that is self- reversing after the force is removed, so that the object returns to its original shape, is called elastic deformation. In other words, elastic deformation is a change in shape of a material at low stress that is recoverable after the stress is removed. This type of deformation involves stretching of the bonds, but the atoms do not slip past each other.
Plastic Deformation Beyond the elastic limit the material undergoes plastic deformation. Unlike elastic deformation, plastic deformation is not recoverable, i.e. the change is permanent. Ductile materials undergo large plastic deformations and waisting before fracturing; brittle materials undergo very little plastic deformation. Also known as placticity
Plastic Deformation Failure by plastic deformation Use the info link to see examples of designs and materials testing, using rapid prototyping
Alloys A mixture containing two or more metallic elements or metallic and non-metallic elements usually fused together or dissolving into each other when molten; "brass is an alloy of zinc and copper Ferrous and nonferrous alloys
Alloys Change the melting point Increase strength, hardness & ductility Change colour Give rise to better casting Change electrical and thermal properties
Iron & Carbon Stainless Steel is an alloy of Carbon and Iron Stainless steel is one of the fastest growing metals. Today, it is difficult to imagine life without this most durable and versatile material. And, it is 100% recyclable.
Steel Stainless steel (steel and 18% chromium, 8% nickel, 8% magnesium) High-speed steel (steel and tungsten) Mild steel (iron and % carbon) Medium carbon steel ( % carbon) High-carbon steel ( % carbon) High tensile steel (low carbon steel & nickel) Manganese steel (1.5% manganese)
Task 1 Explain the term alloy and give examples of two ferrous and two non- ferrous alloys. Give one example of how the following metals might be used and state which of the materials characteristics makes it particularly appropriate for the application that you have given. Cast ironCopper AluminiumBrass
In search of superalloys
Superalloys A superalloy, or high-performance alloy, is an alloy that exhibits excellent mechanical strength and creep resistance at high temperatures, good surface stability, and corrosion and oxidation resistance. Superalloys typically have an austenitic face-centred cubic crystal structure.
Superalloys A superalloy's base alloying element is usually nickel, cobalt, or nickel-iron. Superalloy development has relied heavily on both chemical and process innovations and has been driven primarily by the aerospace and power industries.
Superalloys Typical applications are in the aerospace industry, eg. for turbine blades for jet engines
Task 2 Define the following words and add a suitable images to illustrate your answer Plastic deformation Elastic deformation Superalloys Creep Oxidisation Malleable Ductile
Links and Revision ed.org/EducationResources/CommunityCollege/Materials/Structure/d eformation.htmhttp://www.ndt- ed.org/EducationResources/CommunityCollege/Materials/Structure/d eformation.htm