activity series: also known as the Electromotive Force Series. This is a listing of the elements according to their potential differences and ability to place other elemental ions in solution.

alloy: a substance that has metallic properties and is made up of two or more chemical elements, of which at least one is a metal.

annealing: a heat treatment of a metal designed to produce a soft, ductile condition. Typically the metal is heated and allowed to cool slowly.

anode: electrode at which electrons are released during corrosion. The half reaction at the anode is called oxidation and the metal is said to be oxidized. The anode is the electrode that disintegrates during corrosion.

bronze: An alloy composed of tin and copper.

cathode: electrode which accepts electrons during corrosion. The half reaction at the cathode is called reduction and the metal is said to be reduced. The cathode is not destroyed during corrosion.

cathodic protection: a more active metal is placed next to a less active metal. The more active metal will serve as an anode and will be corroded instead of the less active metal. The anode is then called a sacrificial anode.

cold-working: a permanent deformation of a metal below its crystallization temperature. Deforming the metal creates more dislocations which entangle, pinning them and thereby strengthening the metal.

corrosion: oxidation-reduction reaction where electrons are released at the anode and taken up at the cathode.

dislocations: linear defects in a crystal.

ductile: can be drawn or stretched into wire and other shapes.

elastic deformation: materials return to their original shape after a small load or stress is applied.

face-centered cubic: crystal arrangement of close-packed layers of particles where three layers of particles alternate positions. This layering is known as ABCABC.

failure: ultimate separation of metal parts due to applied loads. i.e. it breaks.

fatigue: the application and release of stresses as metal is used which cause small cracks to grow, during many cycles of application, until they fracture.

grain: a crystal (ordered arrangement of atoms).

grain boundary: the interface between the grains or crystals.

Hall Process: an electrolytic technique to refine aluminum from its ore.

hardening: heating and rapidly cooling steel.

heat treating: modification of properties and structure of alloys by specific heating and cooling cycles.

hexagon closest packing (HCP): crystal arrangement of layers of particles where two layers alternate positions. The layering is known as ABAB.

malleable: can be hammered into a sheet.

martensite: a super-saturated solid solution of carbon in ferrite. The carbon atoms distort the BCC ferrite into a BC-tetragonal structure.

metallic bonding: bond formed by positive ions surrounded by a sea of valence electrons.

ore: a natural mineral deposit that contains enough valuable minerals to make it profitable to mine at the current technology.

oxide: a compound of oxygen with some other chemical element.

oxidation: the half of an electrochemical reaction where electrons are released. Oxidation occurs at the electrode called the anode.

pinned: the dislocations in a crystal get tangled or attached to atoms of an alloying agent.

plastic deformation: materials remain deformed after a load is added and then removed.

quenched: cooled rapidly.

reduction: the half of an electrochemical reaction where electrons are taken up. Reduction occurs at the cathode.

reduction of metals: changing a metal ion to a neutral atom by the addition of electrons.

steel: an iron-carbon alloy, malleable in some temperature range as initially cast. Steel usually contains some other alloying elements such as silicon, manganese, etc. as well as impurities such as sulfur and phosphorus.

strength: a measure of the ability of a material to support a load.

stress: the internal forces produced by application of an external load, tending to displace component parts of the stressed material. It is defined as the force (load) divided by the area on which it acts.

toughness: the ability to aborb energy of deformation without breaking. High toughness requires both high strength and high ductility.

unit cell: The smallest repeating array of atoms in a crystal.

Metals Table of Contents
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