Term
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Definition
| The energy required to cause a particular reaction to occur |
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Term
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Definition
| three step heat treatment used primarily for non ferrous alloys and stainless steels where the material is heated to a single phase region, quenched to form a supersaturated solid solution and then alloyed to age either naturally at room temperature or artificially at an elevated temp , a type of dispersion strengthening that forms a coherent precipitate |
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Term
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Definition
| the characteristic of a material being able to exist in more than one crystal structure |
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Term
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Definition
| a metallic material that is obtained by chemical combinations of different elements, typically have better properties than pure metals |
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Term
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Definition
| materials that have no long range order only short range order |
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Term
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Definition
| a negatively charged ion produced when an atom usually of a non metal accepts one or more electrons |
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Term
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Definition
| having different properties in different directions |
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Term
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Definition
| a heat treatment that typically involves heating a metallic material to a high temperature for an extended period of time in order to lower the dislocation density and impart ductility |
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Term
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Definition
| aging at temps greater than room temp but lower than the solvus temp |
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Term
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Definition
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Term
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Definition
| heating a steel or cast iron to a temperature where homogeneous austenite can form, first step of most heat treatments for steel and cast iron |
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Term
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Definition
| two phase microconstituent containing ferrite and cementite |
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Term
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Definition
| a phase diagram that has two components |
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Term
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Definition
| the energy required to separate two atoms an infinite distance apart, measure of the bond strength |
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Term
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Definition
| The ability of a material to bond directly with living tissues when implanted |
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Term
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Definition
| The condition of being compatible with living tissue or a living system by not being toxic or injurious and not causing immunological rejection |
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Term
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Definition
| the fourteen possible lattices that can be created using lattice points, examples of some of these include HCP, FCC and BCC |
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Term
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Definition
| the direction and distance a dislocation moves in each step |
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Term
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Definition
| alloys that are poured from the molten state into a mold and then allowed to solidify to produce a desired shape |
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Term
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Definition
| ferrous alloys containing sufficient carbon so that the eutectic reaction occurs during solidification |
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Term
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Definition
| a positively charged ion produced when an atom, usually of a metal, gives up its valence electrons |
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Term
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Definition
| hard, brittle, intermetallic compound Fe3C |
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Term
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Definition
| an inorganic material with high melting temp and usually hard and brittle |
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Term
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Definition
| a region of small randomly oriented grains that forms at the surface of a casting as a result of heterogeneous nucleation |
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Term
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Definition
| directions in a crystal along which atoms are in contact |
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Term
| coefficient of thermal expansion |
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Definition
| the amount by which a material changes its dimensions when the temperature changes |
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Term
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Definition
| a crystalline precipitate that forms from solid solution with the orientation that maintains continuity between the crystal lattice of the precipitate and the lattice of the matrix, usually accompanied by some strain in both lattices. |
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Term
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Definition
| deformation of a material below its recrystallization temperature |
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Term
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Definition
| a region of elongated grains having a preferred orientation that forms as a result of competitive growth during the solidification of a casting |
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Term
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Definition
| the basic materials that make up a composite material and include matrix, reinforcement and the interface |
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Term
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Definition
| the number of nearest neighbors to an atom in its atomic arrangement |
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Term
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Definition
| an addition polymer produced by joining more than one type of monomer |
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Term
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Definition
| a very strong type of primary bond formed between two atoms when the atoms share their valence electrons |
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Term
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Definition
| time dependent permanent deformation at high temperatures occurring at constant load or constant stress |
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Term
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Definition
| the attack of metal surfaces by a stagnant solution in crevices, for example in nuts and rivet heads. When dust, sand and other corrosive substances are deposited on surfaces, they create an environment where water will accumulate and corrode the part. It can happen between two metals or between a metal and a nonmetal. This causes damage to the metallic part, which is initiated by the concentration gradient in chemicals. Oxygen causes an electrochemical concentration cell outside the crevice. This is a differential aeration cell where the air present is oxygen. In the crevice (the cathode), the pH and the oxygen content increases. However, this is the opposite for the chlorides; they are lower. |
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Term
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Definition
| the minimum size that must be formed by atoms clustering together in a liquid before a solid particle is stable enough and can grow, less than the critical radius the particle is an embryo, greater than the critical radius the particle is a nucleus |
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Term
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Definition
| attaching chains of polymers together to produce a three-dimensional network polymer |
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Term
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Definition
| the change in the slip system of a dislocation, ability of Goldie to find a new path |
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Term
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Definition
| the arrangement of atoms in a material into a regular repeatable lattice, |
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Term
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Definition
| materials that have long range arrangement of their atoms in a regular and repeatable manner, comprised of many small crystals or grains |
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Term
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Definition
| temperature at which a polymer burns, chars or decomposes |
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Term
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Definition
| the number of monomers in a polymer; the length of the molecular chain |
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Term
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Definition
| separation of individual plies of a fiber-reinforced composite |
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Term
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Definition
| the tree like structure of a solid that grows when an undercooled liquid nucleates |
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Term
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Definition
| crystallization of glass to form glass ceramic |
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Term
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Definition
| crystallographic directions that all have the same characteristics denoted by <> |
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Term
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Definition
| a line imperfection in a crystalline material; movement of these helps explain how a metallic material plastically deforms, interference with the movement of these helps explain how metallic materials are strengthened |
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Term
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Definition
| increasing the strength of a material by mixing more than one phase |
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Term
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Definition
| the ability of a material to be permanently deformed without breaking |
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Term
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Definition
| a dislocation introduced to the lattice by adding an extra half plane of atoms, the burgers vector for an edge dislocation is perpendicular to the dislocation line |
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Term
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Definition
| deformation that is recovered when the load is removed (not permanent) |
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Term
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Definition
| polymers possessing exceptional elastic deformation due to the fact that the molecular chains that comprise these materials are highly coiled |
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Term
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Definition
| the relative tendency of an atom to accept an electron and become an anion, strongly electronegative atoms readily accept electrons |
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Term
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Definition
| a tiny particle of solid that forms from the liquid as the atoms cluster together but is not stable enough to grow, smaller than the critical radius |
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Term
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Definition
| the amount that a material deforms per unit length when pulled or pushed |
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Term
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Definition
| the applied load divided by the original cross-sectional area |
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Term
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Definition
| a region of randomly oriented grains in the center of a casting produced as a result of widespread nucleation |
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Term
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Definition
| three phase reaction where the liquid phase changes to two solid phases upon cooling |
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Term
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Definition
| three phase reaction where a solid phase transforms into two solid phases upon cooling |
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Term
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Definition
| a solid solution of one or more elements in BCC iron, the BCC phase on the iron carbide phase diagram |
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Term
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Definition
| process for producing fiber reinforced composites in which continuous fibers are wrapped around a form or mandrel the fibers may be prepregged or the filament wound structure may be impregnated to complete the production of the composite |
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Term
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Definition
| The microstructural mechanism responsible for dislocation multiplication during strain hardening, a pinned dislocation under applied stress produces additional dislocations |
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Term
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Definition
| gradual wear by means of rubbing or gnawing action between two surfaces. Fretting corrosion is a combined action of fretting as well as corrosion, which involves corrosion at points where two metal surfaces make contact by means of a rubbing action. |
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Term
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Definition
| amorphous material derived by cooling a melt |
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Term
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Definition
| ceramics formed in the glassy state and allowed to partially crystalize during heat treatment, an example of glass ceramic is corning were |
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Term
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Definition
| the temperature range below which the amorphous polymer assumes a rigid glassy structure also known as glass transition temperature |
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Term
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Definition
| a portion of solid material within which the lattice is identical and is oriented in only one direction |
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Term
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Definition
| diffusion of atoms along a grain boundary |
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Term
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Definition
| the addition of heterogeneous nuclei in a controlled manner to increase the number of grains in a casting |
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Term
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Definition
| the physical process by which a new phases increases in size |
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Term
| Guinier Preston (GP) zones |
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Definition
| Tiny clusters of atoms that form early on in the age hardening process |
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Term
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Definition
| A measure of the depth to which a specific ferrous alloy may be hardened by the formation of martensite upon quenching from a temperature above the upper critical temperature, the Jominy Bar test is used to provide a measure of hardenability |
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Term
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Definition
| a quick easy and cheap test that measures the resistance of a material to penetration by a sharp object, some examples include the Brinell and Rockwell tests |
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Term
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Definition
| formation of a critically sized solid from the liquid on an impurity surface of the surface of the mold wall |
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Term
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Definition
| formation of a critically sized solid from the spontaneous cluster of atoms due to severe undercooling |
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Term
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Definition
| a lightweight but stiff assembly of aluminum strip joined and expanded to form the core of sandwich structure |
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Term
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Definition
| deformation of a material above the recrystallization temperature |
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Term
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Definition
| necessary but not sufficient conditions that an alloy system must meet in order to display unlimited solubility - includes same crystal structure, similar atomic size, same valence and similar electronegativity |
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Term
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Definition
| for an alloy system displaying a eutectic, an alloy for which the concentration of the solute is greater than the eutectic composition |
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Term
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Definition
| for an alloy system displaying a eutectic an alloy for which the concentration of the solute is less than the eutectic composition |
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Term
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Definition
| a measure of the energy absorbed during the fracture of a specimen of standard dimensions and geometry when subjected to very rapid loading, Charpy and Iron tests re used to measure this parameter which is important in assessing the ductile to brittle transition behavior of a material. |
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Term
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Definition
| the addition of an agent to molten cast iron that provides nucleation sites at which graphite precipitated during solidification |
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Term
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Definition
| This is a corrosion type that attacks the boundaries of the metal crystallites, as opposed to attacking the surface of the metal. Intergranular corrosion can also be referred to as intergranular attack under a condition known as grain boundary depletion |
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Term
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Definition
| a compound of two or more metals that has unique composition and structure, most intermetallics are hard and brittle |
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Term
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Definition
| a point defect produced when an atom is placed into the lattice at a site that is normally not a lattice point (in between space) |
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Term
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Definition
| diffusion of different atoms from one interstitial position to another |
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Term
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Definition
| a location between the normal atom or ions in a crystal into which another atom can be placed (in-between spots) |
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Term
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Definition
| The bond formed between two different atoms when on atom donates its valence electrons to the second atom and the two ions are held together by columbic (strong electrostatic attraction) forces. |
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Term
| Isomorphous phase diagram |
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Definition
| a phase diagram that displays unlimited solid solubility (single solid phase) |
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Term
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Definition
| Having the same properties in all directions |
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Term
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Definition
| test used to evaluate hardenability, an austenitized steel bar is quenched atone end only thus producing a range of cooling rates |
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Term
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Definition
| a collection of points that divide space into smaller equally spaced segments, the regular geometrical arrangements of points in crystal space |
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Term
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Definition
| the lengths and sides of the unit cell and the angles between those sides |
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Term
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Definition
| a technique used to determine the amount of each phase in a two phase system |
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Term
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Definition
| the temperature on a phase diagram at which the first solid begins to form |
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Term
| local solidification time |
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Definition
| The time required for a particular location in a casting to solidify once nucleation has begun |
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Term
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Definition
| cast iron obtained by a lengthy heat treatment during which cementite decomposes to produce rounded clumps of graphite, good strength, ductility and toughness are obtained |
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Term
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Definition
| a metastable phase formed in steel by diffusionless athermal transformation, this phase is very strong but very brittle |
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Term
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Definition
| the continuous phase in a two phase material or for a composite, the continuous material that holds the reinforcement together and helps to transfer stresses |
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Term
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Definition
| the continuous phase in a composite, the composites are named after the continuous phase, holds reinforcement together and helps transfer load |
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Term
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Definition
| properties of a material such as strength that describes a materials response to an applied force, these properties are sensitive to the microstructure of a material |
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Term
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Definition
| a type of primary bond where positively charged atom cores are held together by the mutually electrostatic attraction to the negatively charged electron cloud or sea of electrons |
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Term
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Definition
| a region where two liquid phases do not mix or are not soluble in one another |
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Term
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Definition
| the slope of the stress strain curve in the elastic region, E |
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Term
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Definition
| the molecule from which a polymer is produced |
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Term
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Definition
| a three phase reaction in which one liquid transforms to a solid and second liquid on cooling |
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Term
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Definition
| spontaneous aging of a supersaturated solid solution at room temperature |
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Term
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Definition
| hardening the surface of steel with nitrogen obtained from a special gas atmosphere |
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Term
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Definition
| an alloy based on a metal other than iron |
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Term
| nonstochiometric intermetallic |
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Definition
| an intermetallic that exists at a range of compositions |
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Term
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Definition
| The steel is then air-cooled, which is a cooling rate of approximately 38 °C (100 °F) per minute. This results in a fine pearlitic structure, and a more-uniform structure. Normalized steel has a higher strength than annealed steel; it has a relatively high strength and ductility |
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Term
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Definition
| the initial stages in a phase transformation, it is evidenced by the formation of small stable particles of the new phase which are capable of growing |
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Term
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Definition
| a tiny stable particle of solid that forms from the liquid as atoms cluster together, the radius of the nucleus is greater than some critical radius |
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Term
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Definition
| a yield strength obtained graphically that describes the stress that gives no more than a specified amount of plastic deformation |
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Term
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Definition
| the fraction of space occupied by atoms |
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Term
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Definition
| a two phase lamellar microconstituent in steel made up of ferrite and cementite, this microstructure is relatively soft and ductile, formed from slow, near equilibrium cooling rates. |
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Term
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Definition
| the total percent increase in length of a specimen during the tensile test |
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Term
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Definition
| a three phase reaction where a liquid and a solid phases transform to a single solid phase upon cooling |
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Term
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Definition
| a three phase reaction where two solid phases transform to a single solid phase upon cooling |
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Term
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Definition
| a material having the same composition structure and properties under equilibrium conditions |
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Term
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Definition
| describe a materials response to an applied field |
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Term
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Definition
| This is a corrosion that occurs in materials that have protective films. It is an attack with localized holes on the metal's surface. The attack can penetrate the metal very rapidly, while some parts of the metal surface remain free from corrosion. Pitting is vigorous when the solution on the metal surface contains chloride, hypochlorite or bromide ions. Other harmful solutions are those that contain fluorides and iodides, while sulfides and water are known to enhance the pitting process |
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Term
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Definition
| the growth of a smooth solid liquid interface where no undercooling is present |
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Term
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Definition
| crystallographic planes that have the same characteristics although their orientation is different, denoted by {} generic planes |
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Term
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Definition
| permanent deformation in a material, for metals, plastic deformation occurs by the movement of dislocations through the material (SLIP) |
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Term
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Definition
| zero dimensional imperfections that are located at a single point, examples include vacancies, substitutional and interstitial |
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Term
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Definition
| a subgrain structure produced during the recovery stages of annealing where the dislocations do not decrease in number but they rearrange themselves into this polygonized substructure |
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Term
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Definition
| polymers are materials made from giant chain like molecules having average molecular weights from 10K to 1 M g/mol built by the joining of many mers or units by chemical bonds...typically carbon based |
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Term
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Definition
| allotropy or being able to exist in more than one crystal structure |
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Term
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Definition
| the temperature of a metal when it is poured into a mold |
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Term
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Definition
| a solid phase that forms during age hardening from the original matrix then the solubility limit is exceeded |
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Term
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Definition
| layers of fibers in unpolymerized resins, after the prepregs are stacked to form a desired structure, polymerization joins the layers together |
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Term
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Definition
| a low temp heat treatment used to eliminate all or part of the effects of cold working in steels |
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Term
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Definition
| a stage in the annealing process where the material is subjected to a low temperature heat treatment (below Trc) causing the dislocations to rearrange themselves into that polygonized substructure this stage of annealing eliminates residual stresses, restores electrical conductivity but does not change the strength of the material |
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Term
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Definition
| a stage in the annealing process where the material is subjected to a medium temperature heat treatment where the dislocations are removed from the material and new grains nucleate and grow, eliminates all of the effects of strain hardening except the dimensional changes |
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Term
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Definition
| the distance from one lattice point to an adjacent lattice point along a specific direction |
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Term
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Definition
| tresses that remain in a solid material after the original cause of the stresses has been removed. Residual stress may be desirable or undesirable. For example, laser peening imparts deep beneficial compressive residual stresses into metal components such as turbine engine fan blades |
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Term
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Definition
| statement that the properties of a composite material are a function of the volume fraction of each material in the composite |
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Term
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Definition
| a composite material constructed of a lightweight low density material surrounded by dense solid layers, the sandwich combines overall light weight with excellent stiffness |
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Term
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Definition
| a dislocation produced by skewing or shearing the crystal one atomic plane, Burgers vector is parallel to dislocation line |
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Term
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Definition
| Relatively weak bond such as van der waals and hydrogen bonds that typical join molecules to one another |
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Term
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Definition
| the random movement of atoms within a pure metal |
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Term
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Definition
| an alloy, such as Nitinol, that "remembers" its original shape and that when deformed returns to its pre-deformed shape when heated. |
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Term
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Definition
| the movement of dislocations in a metal which leads to permanent deformation |
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Term
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Definition
| a homogeneous crystalline phase that contains two or more chemical species, both substitutional and interstitial solid solutions are possible |
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Term
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Definition
| the temperature on a phase diagram below which all the liquid has completely solidified |
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Term
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Definition
| the first step in age hardening where the material is heated above its solvus temperature to form a single phase solid solution by dissolving the precipitate particles |
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Term
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Definition
| a solubility line on a phase diagram that separates a single solid phase region from multiple phase region, indicates the solubility limit of a material |
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Term
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Definition
| steels having more than 11% cr, providing excellent corrosion resistance |
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Term
| stoichiometric intermetallic |
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Definition
| an intermetallic compound that exists at a single composition, seen on the phase diagram as a vertical line |
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Term
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Definition
| a method of strengthening a metal by increasing the number of dislocations by plastically deforming the metal |
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Term
| Stress Corrosion Cracking |
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Definition
| progressive fracturing that occurs in metals as a result of the combined influence of tensile stress and a corrosive environment. Structural failure due to SCC can be very unpredictable — failure could occur after as little as a few hours of exposure, or the equipment could continue to function normally for months or even years. Metal components frequently experience SCC, and virtually all alloy systems are susceptible to SCC by specific corrodents under specific conditions |
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Term
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Definition
| a reduction of the stress acting on a material over a period of time at a constant strain due to viscoelastic deformation |
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Term
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Definition
| a point defect in a crystalline material produced an atom is removed from a regular lattice positon and replaced with another type of atom |
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Term
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Definition
| the pouring temperature minus the equilibrium freezing temp |
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Term
| supersaturated solid solution |
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Definition
| solution that contains more of the dissolved material than could be dissolved by the solvent under normal circumstances, forms after a material has been solution treated than quenched in the process of aging |
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Term
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Definition
| imperfections such as grain boundaries that form a two dimensional plane within the crystal |
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Term
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Definition
| diffusion along the surface of a material, fastest |
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Term
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Definition
| describes the location in the polymer chain of atoms or atom groups is nonsymmetrical monomers |
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Term
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Definition
| a shorthand notation used for aluminum and other alloys that explains the heat treatment employed on that material (includes letters O, H,T, F, W) |
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Term
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Definition
| the microconstituent of ferrite and cementite formed when martensite is tempered. |
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Term
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Definition
| process where a hardened steel or cast iron is reheated to some temperature below the eutectoid temperature for the purpose of decreasing the hardness and increasing the toughness by restoring some of the ductility, in steels tempering is generally done by heating the material to the appropriate temperature and then allowing the material to cool slowly in air |
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Term
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Definition
| the stress that corresponds to the maximum load in a tensile test |
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Term
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Definition
| a plateau on the cooling curve during solidification caused by the latent heat of fusion that is emitted during solidification which effectively heats the cooling liquid |
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Term
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Definition
| linear or branched polymers in which chains of molecules are not interconnected to one another, easily processed |
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Term
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Definition
| polymers that are heavily cross-linked to produce a strong three dimensional network structure |
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Term
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Definition
| a horizontal line drawn in a two phase region of a phase diagram that helps to determine the composition of each phase |
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Term
| total solidification time |
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Definition
| the time required for a casting to solidify after the casting has been poured into the mold |
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Term
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Definition
| a qualitative measure of the impact resistance of a material, a function of the strength and ductility of a material, can be determined from the area under the true stress-strain curve |
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Term
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Definition
| the temperature below which a material behaves in a brittle manner in an impact test |
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Term
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Definition
| the temperature to which a liquid metal must be cooled below the equilibrium freezing temperature before nucleation occurs |
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Term
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Definition
| a subdivision of the lattice that still retains the overall characteristics of the entire lattice; the basic building block of a crystalline material |
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Term
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Definition
| a point defect where an atom is missing from a regular lattice site |
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Term
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Definition
| mechanism of diffusion where a diffusing atom leaves a regular lattice position to fill a vacancy site |
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Term
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Definition
| the number of electrons in an atom that takes place in bonding or chemical reactions |
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Term
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Definition
| the deformation of a polymer by viscous flow of the chains or segments of the chain where the stress is applied |
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Term
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Definition
| the slowest type of diffusion where the diffusing species moves through the interior of the volume of the grains where the atoms are most efficiently packed |
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Term
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Definition
| cross linking elastomer chains of introducing sulfur or other chemicals |
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Term
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Definition
| alloys that are shaped by a deformation process |
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