4482880
| Questão | Responda |
| 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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