First Evaluation Review: MATERIALS APPLICATIONS

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Flashcards by euribelam, updated more than 1 year ago
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Created by euribelam about 5 years ago
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Flashcards on First Evaluation Review: MATERIALS APPLICATIONS, created by euribelam on 02/10/2016.

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Question Answer
Type of ATOMIC BOND present in: Metallic Bond
Covalent Bond It ocurrs when elements share valence electrons between two or more atoms. Non metal+ Non metal
Ionic Bond Ocurrs when one atom gives its valence electrons to a different atom. Metal+Non metal
Aluminum, copper, silver, gold are examples of materials with this type CRYSTALLINE STRUCTURE. FCC
Metals with BCC structure Chromium (Cr) Iron (Fe) Niobium(Nb) Potassium (K) Sodium (Na)
Titanium is a metal with this type CRYSTALLINE STRUCTURE. HCP
The material fails because of the presence of a flaw Fracture
Fatigue The material fails due to repetitive stress. Work-cicle related
In this type of failure the material fails because of the temperature and stress. Creep
Nuclei First solid nanocrystals formed during solidification.
Is a tiny particle of solid that forms from the liquid as atoms cluster together. Is unstable can grow into a stable nucleus or redissolve. Enbryo
The minimum size that must be formed by atoms clustering together in the liquid before the solid particle is stable and begins to grow. Critical radius
Undercooling The temperature to which the liquid metal must cool below the equilibrium freezing temperature before nucleation occurs.
To transformate the solid to liquid we need to increase the temperature above its boiling temperature. Superheat
Type of nucleation that occurs in high undercooling Homogeneous Nucleation
Type of nucleation from a preexisting surfaces, like impurities in the molten metal or in the walls of the mold. Heterogeneous Nucleation
Inocutation Process to intentionally introduce nucleating particles in the liquid
Specific Heat The heat required to change the temperature of a unit of weight one degree.
Plannar Growth The growth of a smooth solid-liquid interface during solidification, when no undercooling of the liquid is present
The treelike structure of the solid that grows when an undercooled liquid solidifies Dentritic Growth
Type of growth mechanism present in not well inoculated liquids. Dentritic Growth
Solidification time The rate at which growth of the solid occurs depends on the cooling rate, or the rate of heat extraction.
SDAS Secondary dentrite arm spacing
To reduce SDAS: Faster cooling rates
Small SDAS: Increase ductility and tensile strength
Points: A=Pouring temperature B= Melting/solidification temperature B-C= Undercooling C-D= Recalescence D-E= Thermal arrest E= solidification complete
Cooling curve for a well inoculated liquid, or pure metal. NO undercooling
Casting product Finished shape produced by the mold.
Simple shape produced by a mold, than requires extensive plastic deformation before finished product is created. Ingot
Cast region of randomly oriented grains in the center of a casting Equiaxed zone
During solidification a material contracts, shrinks, as much as: 7%
Pipe Solidification Defect that occurs when one surface solidifies more slowly than the others, usually is in the surface of the casting.
Extra reservoir of metal, adjacent and conected to the casting to solve solidification defects Riser
Gas Porosity Bubbles of gas trapped within a casting during solidification
Gas produced during aluminum solidification Hydrogen
In this type of welding process the filler metal is brass. Brazing
Solid-Solution Strengthening Strengthening by the formation of ONE phase
Dispersion Strengthening Strengthening by the formation of TWO phases
Characteristics of a phase -Same structure or atomic arragement -Same composition and properties - A definite interface between the phase and any surrounding or adjoining phases.
Triple point A point on the diagram at which the solid, liquid and gaseous phases coexist under equilibrium conditions.
1 + C= F + P Parts C= # of components F= freedom degrees P= phases present
Fredom degrees=2 The temperature and composition can change with out changing the phase.
Freedom degrees over a line in any phase diagram 1
Part in a phase diagram where the freedom degrees=0 Triple point
Unlimited solubility When the amount, of one material that will dissolve in a second material without creating a second phase
When only a maximum amount of a solute material can be dissolved in a solvent material. Limited solubility
Conditions for unlimited solid solubility. Size factor Crystal structure Valence Electronegativity
Electrical conductivity and ductility is better in: pure metals
Unary phase diagram
Isomorphus phase diagrams Binary phase diagrams
Ternary phase diagram Phase diagram with 3 components (elements or compounds)
Solidus Temperature The temperature below which the alloy is 100% solid.
The temperature above which the alloy is 100% liquid. Liquidus Temperature
Segregation The presence of composition differences in a material, often caused by insufficient time for diffusion during solidification.
Homogenization heat treatment The heat treatment used to reduce the microsegregation caused during nonequilibrium solidification
Eutectic reaction Solidification where a liquid freezes to simultaneously form two solid phases.
Eutectoid Reaction One solid phase reacts to form two different solid phases.
Intermetallic compound A compound formed of two or more metals that has its own unique composition, crystal structure, and properties.
Peritectic reaction A solid and a liquid combine to produce a second solid on cooling
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